Task - The fundamental unit of work scheduled by CICS such as Read from file, write to file, read from workstation, write to workstation, initiate another task, call another function and so on.

Transaction - An entity to initiate/invoke a task for execution.
A transaction is 1 to 4 characters long.

A transaction is a piece of processing initiated by single request, usually by end user at a terminal.

A single transaction will consist of one or more application programs that, when run, will carry out the processing needed.

Program - Set of instructions to achieve a task.

LUW (Logical unit of work) tells that the piece of work should be done either completely or not done at all.

NON AID keys - Alphabets, numbers, punctuation etc. CICS will NOT even know if user presses any NON AID key which means it can’t detect NON AID keys when pressed.

AID Keys - Attention Identifier keys are Function keys ( PF1 to PF24 ), Enter, CLEAR and PA1 to PA3 keys. CICS detect only AID keys when pressed.

After text is typed, CICS takes the control once user presses any AID key.

PA1 - Alt + PF1

MDT - Modified Data Tag

FRSET - Flag ReSET

Control Programs

CICS nucleus is constructed by control programs

• Terminal Control Program (TCP) - is used to receive messages from the terminal.
  It also maintains hardware communication requirements.


• Task Control Program (KCP) - is used to simultaneously control the execution of tasks and its related properties.
  It also handles all issues related to Multitasking.


• Program Control Program (PCP) - is used to locate and load programs for execution. It transfers the control between two programs and at the end, it returns the control to CICS.


• File control Program (FCP) - provides an application program with the services like read, write, insert, update or delete records in a file.


• Storage Control Program (SCP) - is used to allocate or de-allocate the memory in CICS region.

Control Tables

The control tables needs to be updated accordingly with application information for the successful execution of CICS application program.

• Terminal Control Table (TCT) - contains the terminal IDs connected to the current CICS region.
  Whenever we login to CICS terminal, an entry is made in TCT.


• Program control table (PCT) - contains Transaction ID and the program associated with it.


• Processing Program table (PPT) - contains the program name or mapset name, task use counter, main storage address, load library address etc.
  When CICS receives the transaction, corresponding program name is picked up from PCT and gets loaded.


• File Control Table (FCT) - contains the information about file names, file types, record length etc.
  All the files names used in CICS must be declared in FCT.

How a transaction processing is done?

Once the user enters transaction ID(eg., TN01) on the CICS terminal, first corresponding program name will be checked in PCT.
Once the program is found in PCT, it checks the main storage address/ Load library address to get the program loaded into the memory for execution.

CICS system transactions

• CESN (CICS Execute SigNon) - This transaction is used to sign on into the CICS region.


• CEDA (CICS Execute Definition and Administration) - This transaction is used by CICS administrators to define CICS table entries and other Admin activities.


• CEMT (CICS Execute Master Terminal) - Used to inquire and update the status of CICS environments.
  This is also used to load a new program, load a copy of the old program into CICS after changes to program.


• CECI (CICS Execute Command Interpreter) - Used to check the syntax of CICS commands.
  Here the command gets executed only if the syntax is correct.


• CEDF (CICS Execute Debug Facility) - Used for debugging the program step-by-step which helps finding the errors.


• CEAC (CICS Execute Abend Codes) - Used to find the explanation for the CICS abend codes.


• CESF (CICS Execute Sign oFf) - Used to sign off from CICS region.

OS allows execution of one or more tasks concurrently and this is called Multitasking.
If one or more concurrent tasks use the same copy of the program, it is called Multithreading.

RE-Entrancy - A re-entrant program cannot modify by itself but can re-enter itself and continue processing after an interruption by OS.

Quasi Reentrancy - A quasi re-entrancy is a re-entrant program in CICS environment which means this program will not modify by itself and can re enter to continue processing after an interruption by CICS.
During interruption, executes other CICS tasks including tasks of same program.

BMS (BASIC MAPPING SUPPORT)

BMS helps to develop formatted screens which are used to communicate between Terminal and CICS program.

MAP - A single screen format which can be designed using BMS macros.
It can have name from 1 to 7 chars.

MAPSET - Collection of maps which are link edited together to form a load module.
It should have a PPT entry and can have name from 1 to 7 chars.

CICS provides BMS to make an application program device independent and format independent.

BMS Macros:

DFHMSD - Used to define MAPSET and its characteristics.

DFHMSD - used to define a MAPSET or Generates MAPSET definition.
MAPSET name is a load module name which should have an entry in PPT.

Parameters:

TYPE - used to define the map and the type.

MAP - Physical map is created

DSECT - Symbolic map is created

&&SYSPARM - Both Physical and Symbolic maps are created

Final - end of the mapset coding.

MODE - Specifies whether the mapset is to be used for input, output or both.

IN - For Input only

OUT - For Output only

INOUT - For both Input and Output

LANG - Specifies the language of the application program into which symbolic description maps in the mapset are copied.

This parameter will be coded only when DFHMSD TYPE=DSECT

STORAGE

AUTO - Both Physical and Symbolic maps will use separate memory locations.

BASE -

CTRL - used to define device control requests.

FREEKB - to unlock keyboard

FRSET - to reset MDT to zero status

ALARM - To display alarm at screen display time

PRINT - sends the map to printer

TERM

type - ensure device independence and need to be coded only when the terminal is not 3270.

TIOAPFX (Terminal Input Output Area PreFiX)

TIOAPFX - yes - Resumes 12 bytes of storage space in the memory to execute CICS commands against the map.

DFHMDI - Used to define a MAP within the Mapset.

SIZE =(Rows,Columns)

- >

specifies the size of the map to be displayed to the user. The standard size is 24 rows 80 columns

LINE

Row number where the map actually starts

COLUMN

Column number where the map actually starts

JUSTIFY

specifies entire map or map fields are left or right justified.

CTRL,TIOAPFX are same as DFHMSD

DFHMDF - used to define new field on the map. We have to code DFHMDF macro for every field present on the map.

POS (row, col)

specifies the position of the field on the map by specifying row and col#.

INITIAL

specifies the initial value of the field. Same as value clause in cobol. i.e

FLDNAME

contains value ‘I LOVE CICS’.

LENGTH

specifies the length of the field.

ASKIP

means Auto skip.
Data cannot be entered in this field. The cursor skips to next field.

IC (Insert Cursor)

specifies the cursor needs to be placed on this field when the map is displayed.
If IC is specified more than once, the cursor is placed in the last field.

PROT

specifies to protect this field from entering or editing the data

UNPROT

specifies to unprotect the field to edit or enter the data

BRT

displays the field with bright intensity

DARK

displays the field with dark intensity

NORM

specifies normal display

COLOR

is used to specify the color for this field

PICIN, PICOUT

are used to specify the length of data fields used as input/output.
(used to specify the picture clause for input and output Cobol variables in the symbolic map)

Here is the complete BMS Macro Source Code for the Customer Inquiry Screen, with all the DFHMSD, DFHMDI and DFHMDF Macros.

        PRINT  NOGEN

INQSET1 DFHMSD TYPE=&SYSPARM,                                          X
               LANG=COBOL,                                             X
               MODE=INOUT,                                             X
               TERM=ALL,                                               X
               DSATTS=COLOR,                                           X
               CTRL=FREEKB,                                            X
               STORAGE=AUTO,                                           X
               TIOAPFX=YES

INQMAP1 DFHMDI SIZE=(24,80),                                           X
               LINE=1,                                                 X
               COLUMN=1

        DFHMDF POS=(1,1),                                              X
               LENGTH=8,                                               X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='CUSTINQ1'

        DFHMDF POS=(1,32),                                             X
               LENGTH=16,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='Customer Inquiry'

TRANSID DFHMDF POS=(1,76),                                             X
               LENGTH=04,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='INQ1'

        DFHMDF POS=(3,01),                                             X
               LENGTH=42,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='Type a customer number. Then press ENTER.'

        DFHMDF POS=(5,01),                                             X
               LENGTH=24,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='Customer number. . . . .'

CUSTNO  DFHMDF POS=(5,26),                                             X
               LENGTH=06,                                              X
               ATTRB=(NORM,UNPROT),                                    X
               COLOR=TURQUOISE,                                        X
               INITIAL='______'

        DFHMDF POS=(5,33),                                             X
               LENGTH=01,                                              X
               ATTRB=ASKIP

        DFHMDF POS=(7,01),                                             X
               LENGTH=24,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='Name and Address . . . :'

LNAME   DFHMDF POS=(7,26),                                             X
               LENGTH=30,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE

FNAME   DFHMDF POS=(8,26),                                             X
               LENGTH=20,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE

ADDR    DFHMDF POS=(9,26),                                             X
               LENGTH=30,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE

CITY    DFHMDF POS=(10,26),                                            X
               LENGTH=20,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE

STATE   DFHMDF POS=(10,47),                                            X
               LENGTH=02,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE

ZIPCODE DFHMDF POS=(10,50),                                            X
               LENGTH=10,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE

MESSAGE DFHMDF POS=(23,01),                                            X
               LENGTH=79,                                              X
               ATTRB=(BRT,PROT),                                       X
               COLOR=TURQUOISE

        DFHMDF POS=(24,01),                                            X
               LENGTH=20,                                              X
               ATTRB=(NORM,PROT),                                      X
               COLOR=TURQUOISE,                                        X
               INITIAL='PF3=Exit PF12=Cancel'

        DFHMSD TYPE=FINAL
               END

CICS MAP

Physical Map
• Physical map is a load module in the load library which contains the information about how the map should be displayed.
• Physical map is coded with BMS Macros.
  This is primarily used by CICS and ensures device independence in the application program.
• BMS macros are assembled separately and link edited into the CICS load library

Symbolic Map>
• Symbolic map is a copybook in the library which is used by CICS application program to send and receive messages from the terminal.
• Symbolic map ensures device and format independence to the application program
• Symbolic map contains all the variable data which is copied into program’s working storage section.

SKIPPER and STOPPER fields:
• Suppose I have coded the length of a field as 10 which means ideally we are able to enter the data on this field for up to 10 chars.
  But, when we display the map and try to enter the data on the same field, it allows us to enter the data of more than 10 chars.
  So, to avoid this situation we use skipper and stopper fields.
• Skipper and stopper fields are -unnamed fields with length of 1- which needs to be specified after actual field.



• Skipper field - When we code the skipper field after an unprotected field and start entering the value on the field, -once the specified length is reached then the cursor moves to the next unprotected field.



NUMBER DFHMDF POS=(01,01), LENGTH=5, ATTRB=(UNPROT,IC) DFHMDF POS=(01,07), LENGTH=1, ATTRB=(ASKIP)

Stopper field - When stopper field is coded after an unprotected field and start entering the value on this field, then once the limit is reached the cursor stops its positioning.

NUMBER DFHMDF POS=(01,01), LENGTH=5, ATTRB=(UNPROT,IC) DFHMDF POS=(01,07), LENGTH=1, ATTRB=(PROT)

Attribute Byte:

The attribute byte of any field stores information about the physical properties of the field.

0&1 - determined by contents of bit 2 to 7 2&3 Protection and shift 00 unprotected alphanumeric 01 unprotected numeric 10 protected stop 11 protected skip 4&5 - Intensity 00 - normal, 01 - normal, 10 - bright, 11 - No display (dark) 6 - Must be zero always 7 - Modified data tag. 0- field has not been modified, 1- field has been modified.

Modified Data Tag (MDT):

A flag which holds single bit and used to specify whether the data can be transferred to the system or not. This is the last bit in MDT.

If MDT = 0, the field is not modified and the data cannot be transferred.

If MDT = 1, the field is modified and the data can be transferred

SEND MAP:

This command sends output data to the terminal

EXEC CICS SEND MAP('map-name') MAPSET('mapset-name') [FROM(data-area)] [LENGTH(data_value)] [DATAONLY] [MAPONLY] [CURSOR] [ERASE/ERASEAUP] [FREEKB] [FRSET] END-EXEC

Parameters in SEND MAP

MAP - Name of the map which we want to send

MAPSET - Name of the mapset which contains the map

FROM - specifies the data area containing the data to be processed

MAPONLY - specifies that only default data from the map is to be written

DATAONLY - specifies that only application program data is to be written

ERASE - To erase the complete screen before displaying what we send to terminal

ERASEUP - To erase the values in unprotected fields

FRSET - Flag ReSET turns off the MDT in attribute byte of all the fields before placing the data which is sending.

CURSOR - to specify the cursor position on the terminal. We move -1 to the L part of the field and then send map to the terminal.

ALARM,FREEKB,PRINT are same

FORMFEED - Makes the printer to restore to the top of the next page before output is printed.

Receive Map:

This command is used to receive input from terminal.

EXEC CICS RECEIVE MAP('map-name') MAPSET('mapset-name') [INTO(data-area)] [FROM(data-area)] [LENGTH(data_value)] END-EXEC

Restricted COBOL verbs:

File i/o statements like READ, WRITE, REWRITE, CLOSE, OPEN, DELETE and START.

File section and Environment division.

System functions like ACCEPT, DATE/TIME

Verbs like DISPLAY, MERGE, STOP RUN, GO BACK

Execute Interface Block (EIB):

EIB lets the program communicate with the execute interface program which process CICS commands.
This contains terminal ID, time of day and response codes.

List of fields in EIB

EIBAID X(1) Aid key pressed

EIBCALEN S9(4) COMP - Length of communication area

EIBDATE S9(7) COMP-3 - Contains current system date

EIBTASKN S9(7) COMP-3 - Contains task number

EIBRCODE X(6) - Return code of the last transaction

EIBTRMID X(4) - contains terminal id

EIBTRNID X(4) - contains transaction id

EIBTIME S9(7) COMP-3 - contains current system time

CICS programs classification

1. Non conversion programs: Human intervention is not required.
   All the required inputs need to be provided before we start executing the program.

Example - Below program displays "Hello World" on the terminal

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-MESSAGE PIC X(30). PROCEDURE DIVISION. * SENDING DATA TO SCREEN MOVE 'HELLO WORLD' TO WS-MESSAGE EXEC CICS SEND TEXT FROM (WS-MESSAGE) END-EXEC * TASK TERMINATES WITHOUT ANY INTERACTION FROM THE USER EXEC CICS RETURN END=EXEC.



2. Conversion Programs: Sending a message to the terminal and receiving the response from user is called conversation.

An online application allows conversation between user and application by a pair of SEND and RECEIVE messages.

• First system sends data to the terminal and waits for the user response.
• The time required for the user to respond to this message is called think time which is very high.
• The user provides necessary input and presses AID key.
• The application processes the input and sends the output.
• The program loaded into the main storage until the task ends.



Drawback - Think time is very high for conversion programs.

Pseudo-conversation program:

Here the system will not wait for user response, instead terminates the transaction once it sends data to the terminal.
The transaction will be started again when user presses any AID key.

After termination, the system allocates resources used by this transaction to other transactions which makes the -best utilization of the resources-.

COMMAREA - is used to pass data between tasks-.
We declare WS-COMMAREA in working-storage section

DFHCOMMAREA - is a special memory area allocated by CICS to every task.
This is-used to pass data between programs either of same transaction or different transactions.
This should be declared in linkage-section under 01 level.
The length of both ws-commarea and dfhcommarea must be same.

WORKING-STORAGE SECTION. 01 WS-COMMAREA. 05 WS-DATA PIC X(10). LINKAGE SECTION. 01 DFHCOMMAREA. 05 LK-DATA PIC X(10).

RETURN statement:

The two types are return statements are

1. Return statement without condition, which terminates task and transaction.
   
   

   EXEC CICS RETURN END-EXEC



2. Return statement with condition,When the return is issued with transaction id (TRNSID) statement, the control returns to CICS with the next transaction ID.
   
   

   EXEC CICS RETURN TRNSID(‘TRANSID’), [COMMAREA(WS-COMMAREA)] END-EXEC

DFHAID is a CICS provided copybook which contains pre-coded set of variables used by application programs.
This copybook can be included in the application program by the statement COPY DFHAID.

Dynamically Modifying attributes of a field:

To modify the attributes of a field we must -include CICS provided copybook DFHATTR in the application program-.
The attribute can be chosen from the list of variables in that copybook and moved to the symbolic variable suffixed with A.

CICS File Handling

CICS allows users to access files in

Random order

Sequential Order

Random access

Most file accesses are random in online because the transactions are not batched and sorted in any order.

The commands used for random processing

READ command reads a record from a file using primary key.

Syntax:

EXEC CICS READ FILE('name') INTO(data-area) RIDFLD(data-area) LENGTH(data-value) KEYLENGTH(data-value) END-EXEC.

FILE - name of the file which is of 8 characters long and should be enclosed in quotes. The file name should have an entry in FCT
INTO - a data-area (variable) into which record is to be read.
RIDFLD - contains key of the record that needs to read
LENGTH - the max number of characters that may be read into data-area specified
KEYLENGTH - Length of the key

Example:

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-STD-REC-LEN PIC S9(4) COMP. 01 WS-STD-KEY-LEN PIC S9(4) COMP. 01 WS-STD-REC-KEY PIC 9(3). 01 WS-STD-REC PIC X(70). PROCEDURE DIVISION. MOVE +70 TO WS-STD-REC-LEN. MOVE ‘100’ TO WS-STD-REC-KEY. MOVE 3 TO WS-STD-KEY-LEN. EXEC CICS READ FILE ('FL001') INTO (WS-STD-REC) LENGTH (WS-STD-REC-LEN) RIDFLD (WS-STD-REC-KEY) KEYLENGTH (WS-STD-KEY-LEN) END-EXEC.

Read command options:

GENERIC is used when we doesn’t know the complete key value.
UPDATE specifies the record is to be obtained for update or deletion. Skipping this option assumes read-only.
EQUAL specifies that we need the record whose key matches exactly with the one specified in RIDFLD
GTEQ specifies that we want the first record whose key is greater than or equal to the key specified

EXEC CICS READ FILE('name') INTO(data-area) RIDFLD(data-area) LENGTH(data-value) KEYLENGTH(data-value) GENERIC UPDATE EQUAL GTEQ END-EXEC.

Read command exceptions

NOTOPEN - file not open
NOTFND - Record not found in the dataset
FILENOTFOUND - No file name entry in FCT
LENGERR - Length of the record doesn’t match with the specified in the command
NOTAUTH - Not authorized to use the file
DUPKEY - If more than one record satisfy the condition of key

WRITE command is used to write new records into a file

The parameters are same as for read except that “Data records will be picked FROM data area specified and writes into a file.

EXEC CICS WRITE FILE(name) FROM(data-area) RIDFLD(data-area) LENGTH(data-value) KEYLENGTH(data-value) END-EXEC.

Following is the example to write a record in 'FL001' file where Student-id is the primary key and a new record with 101 student id will be written in the file:

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-STD-REC-LEN PIC S9(4) COMP. 01 WS-STD-KEY-LEN PIC S9(4) COMP. 01 WS-STD-REC-KEY PIC 9(3). 01 WS-STD-REC PIC X(70). PROCEDURE DIVISION. MOVE +70 TO WS-STD-REC-LEN. MOVE ‘101’ TO WS-STD-REC-KEY. MOVE 3 TO WS-STD-KEY-LEN. MOVE '101Mohtahim M TutorialsPoint' TO WS-STD-REC. EXEC CICS WRITE FILE ('FL001') FROM (WS-STD-REC) LENGTH (WS-STD-REC-LEN) RIDFLD (WS-STD-REC-KEY) KEYLENGTH (WS-STD-KEY-LEN) END-EXEC.

Write command exceptions are same as read command exceptions

REWRITE command is used to modify existing record in the file.

Before REWRITE the record must be read with READ UPDATE command. The parameters are same as write

EXEC CICS REWRITE FILE (name) FROM (data-area) LENGTH (data-value) END-EXEC.

Example

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-STD-REC-LEN PIC S9(4) COMP. 01 WS-STD-KEY-LEN PIC S9(4) COMP. 01 WS-STD-REC-KEY PIC 9(3). 01 WS-STD-REC PIC X(70). PROCEDURE DIVISION. MOVE +70 TO WS-STD-REC-LEN. MOVE ‘101’ TO WS-STD-REC-KEY. MOVE 3 TO WS-STD-KEY-LEN. EXEC CICS READ FILE ('FL001') INTO (WS-STD-REC) LENGTH (WS-STD-REC-LEN) RIDFLD (WS-STD-REC-KEY) KEYLENGTH (WS-STD-KEY-LEN) UPDATE END-EXEC. MOVE '100Mohtahim M TutorialsPnt' TO WS-STD-REC. EXEC CICS REWRITE FILE ('FL001') FROM (WS-STD-REC) LENGTH (WS-STD-REC-LEN) END-EXEC.

Rewrite command exceptions-

NOTOPEN, LENGERR, NOTAUTH

INVREQ specifies rewrite without prior READ with UPDATE

NOSPACE specifies no enough space in the dataset

DELETE command is used to delete a record from a file.

Before Delete, we have to READ the record with UPDATE

EXEC CICS DELETE FILE('name') RIDFLD(data-value)END-EXEC.

Delete command exceptions

NOTOPEN, NOTFOUND, NOTAUTH, INVREQ, FILENOTFOUND

Sequential Access

STARTBR(START Browse) tells the CICS from where to start reading the file.

FILE and RIDFLD are same as READ.

Only GTEQ and EQUAL are allowed.

File browsing is strictly Read-Only, so UPDATE is not allowed.

Syntax:

EXEC CICS STARTBR FILE ("name") RIDFLD (data-value) KEYLENGTH(data-value) GTEQ/EQUAL/GENERIC END-EXEC.

READNEXT is to proceed reading the record starting from first record and in sequence one by one

READPREV is to proceed reading the file from backwards.

RIDFLD contains the key of the record which is currently read.

Syntax:

EXEC CICS READNEXT/READPREV FILE ('name') INTO (data-value) LENGTH (data-value) RIDFLD (data-value) END-EXEC

RESETBR resets the starting point of the file in the middle of the browse

Syntax:

EXEC CICS RESETBR FILE ('name') RIDFLD (data-value) GTEQ END-EXEC.

ENDBR allows us to end the browse once we finish reading the file sequentially

Syntax:

EXEC CICS ENDBR FILE ('name') END-EXEC.

CICS - Error Handling

CICS error handling commands are

Handle condition specifies the label (para) to which control is to be passed when the condition arises.
We must include the name of the condition and a label to which control is to be passed.

Example:

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. PROCEDURE DIVISION. EXEC CICS HANDLE CONDITION DUPKEY(X0000-DUPKEY-ERR-PARA) NOTFND(X000-NOT-FOUND-PARA) ERROR(X0000-GEN-ERR-PARA) END-EXEC. X0000-DUPKEY-ERR-PARA. DISPALY 'Duplicate Key Found'. X0000-NOT-FOUND-PARA. DISPLAY 'Record Not Found'. X0000-GEN-ERR-PARA. DISPLAY 'General Error'.

As per the above program, if DUPKEY condition arises, then the control will be passed to X0000-DUPKEY-ERR-PARA

Handle Abend:

When a program abends abnormally, CICS searches for an active abend exit starting from a logical level of an application program to the higher levels.
The control is given to the first active abend exit found.

Example:

EXEC CICS HANDLE ABEND PROGRAM(name) LABEL(Label) CANCEL RESET END-EXEC

Program or label name is used to transfer control to program or para when abend occurs.
CANCEL cancels previous HANDLE CONDITIONS
RESET to reactive previously cancelled HANDLE ABEND

ABEND command terminates the task abnormally.
We can define user defined abend codes using this command

EXEC CICS ABEND> ABCODE(code) END-EXEC.

Example:

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. PROCEDURE DIVISION. EXEC CICS ABEND ABCODE(D100) END-EXEC.

Ignore condition specifies no action should be taken when a particular abend or error occurs.

Syntax:

EXEC CICS IGNORE CONDITION CONDITION(para) END-EXEC

Nohandle specifies no action should be taken for any exceptions conditions that may occur while executing CICS commands.
It can be used with Read, Write, Delete etc.

Syntax:

EXEC CICS program statements NOHANDLE END-EXEC.

Example - Below program will not abend if the read statement fails

IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. PROCEDURE DIVISION. EXEC CICS READ FILE('FILE1') INTO(WS-FILE-REC) RIDFLD(WS-STDID) NOHANDLE END-EXEC.

Commands used for program control serices

XCTL command is used to pass the control from one program to another program of the same level.
It doesn’t expect the control back (similar to goto statement).

Below example transfers control to the program ‘prog2’ with 100 bytes of data

IDENTIFICATION DIVISION. PROGRAM-ID. PROG1. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-COMMAREA PIC X(100). PROCEDURE DIVISION. EXEC CICS XCTL PROGRAM ('PROG2') COMMAREA (WS-COMMAREA) LENGTH (100) END-EXEC.

LINK command is used to transfer control to another program of lower level.

IDENTIFICATION DIVISION. PROGRAM-ID. PROG1. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-COMMAREA PIC X(100). PROCEDURE DIVISION. EXEC CICS LINK PROGRAM ('PROG2') COMMAREA (WS-COMMAREA) LENGTH (100) END-EXEC.

LOAD is used to load a program or table

EXEC CICS LOAD PROGRAM(‘name’) END-EXEC

RELEASE is used to release a program or table

EXEC CICS RELEASE PROGRAM(‘name’) END-EXEC

RETURN is used to return the control to next higher logical level

EXEC CICS RETURN PROGRAM ('name') COMMAREA (data-value) LENGTH (data-value) END-EXEC.

Interval Control operations:

ASKTIME requests current date and time or timestamp.
This can later be moved to working-storage variable in the program.

EXEC CICS ASKTIME [ABSTIME(WS-TIMESTAMP)] END-EXEC.

FORMATTIME formats the timestamp into the required format.

EXEC CICS FORMATTIME ABSTIME(WS-TIMESTAMP) [YYDDD(WS-DATE)] [YYMMDD(WS-DATE)] [YYDDMM(WS-DATE)] [DATESEP(WS-DATE-SEP)] [TIME(WS-TIME)] [TIMESEP(WS-TIME-SEP)] END-EXEC.

Any transaction in the CICS region can access common work area and there is only one CWA for entire CICS region.

Transaction work area (TWA) is used to pass data between application programs which belong to same transaction.
TWA exists only during the transaction.

-Temporary Storage Queue (TSQ)-

• A queue of records which are created, read and deleted by different tasks or programs in the same CICS region.
• A record within a TSQ is identified by item number and can be read sequentially or directly.
• The records in the TSQ are accessible until the TSQ is explicitly deleted.
• The TSQs may be written in main storage or auxiliary storage in DASD.
• TSQs can be accessed by programs and transactions from the same CICS region.

WRITEQ TS allows you to write records into a TSQ.

If no such queue exists, one will be created and writes records into it.

TSQ is identified by queue ID 1-8 bytes.

EXEC CICS WRITEQ TS QUEUE ('queue-name') FROM (queue-record) [LENGTH (queue-record-length)] [ITEM (item-number)] [REWRITE] [MAIN /AUXILIARY] END-EXEC.



• QUEUE - specifies the name of the TSQ.
• FROM - specifies the record to be written into the queue
• LENGTH - specifies length of the record
• ITEM - specifies the item number to be assigned to the record
• REWRITE - is used to update the existing record in the queue
• MAIN/AUXILIARY option - is used to store record in MAIN/AUXILIARY
• AUXILIARY - is default

READQ TS allows you to read the data in TSQ

EXEC CICS READQ TS QUEUE ('queue-name') INTO (queue-record) [LENGTH (queue-record-length)] [ITEM (item-number)] [NEXT] END-EXEC.

NEXT specifies the next logical data item to be read

DELETEQ TS allows you to delete an entire TSQ

EXEC CICS DELETEQ TS QUEUE ('queue-name') END-EXEC.

Transient Data Queue (TDQ) is the queue which can be created and delete quickly.

The contents in the Queue can be read only once as they get destroyed after read is performed.

Allows only sequential access.

TSQ identified by 1 to 4 char name called destinationID which must be registered in DCT (Destination control table).

Intrapartition TDQ - Allows sequential access and once the record is read, it is deleted from queue.

Extrapartition TDQ - Once the record is read, record is not deleted from the queue.

WRITEQ TD - used to write into TDQ and they are always written to a file

EXEC CICS WRITEQ TD QUEUE ('queue-name') FROM (queue-record) [LENGTH (queue-record-length)] END-EXEC.

READQ TD - used to read the TDQ

EXEC CICS READQ TD QUEUE ('queue-name') INTO (queue-record) [LENGTH (queue-record-length)] END-EXEC.

DELETEQ TD – used to delete the TDQ

EXEC CICS DELETEQ TD QUEUE ('queue-name') END-EXEC