💬 Q&A Solutions

COMMIT saves all changes since the last COMMIT and releases locks.

When to COMMIT:

• After processing a logical unit of work
• Periodically in long-running batch (every N records)
• Before ending the program successfully

Frequency Guidelines:

• Too frequent: Performance overhead
• Too rare: Lock contention, large log
• Typical: Every 100-1000 records in batch

Best Practice:

MOVE 0 TO WS-COMMIT-COUNT.

PERFORM PROCESS-RECORD.

ADD 1 TO WS-COMMIT-COUNT.
IF WS-COMMIT-COUNT >= 500
    EXEC SQL COMMIT END-EXEC
    MOVE 0 TO WS-COMMIT-COUNT
END-IF.

Note: In CICS, syncpoint (COMMIT) happens automatically at task end. Explicit SYNCPOINT is rarely needed.

Pseudo-conversational programming is a technique where the program ends between user interactions, freeing system resources.

How it works:

1. Program sends screen to user and ends (RETURN TRANSID)
2. User enters data and presses Enter
3. CICS starts a new task with same program
4. Program retrieves saved data from COMMAREA
5. Process continues

Benefits:

• Efficient resource usage
• Better response times
• More concurrent users

Implementation:

* End task, wait for user
EXEC CICS RETURN
    TRANSID('MENU')
    COMMAREA(WS-COMM)
    LENGTH(100)
END-EXEC.

* On return, check EIBCALEN
IF EIBCALEN = 0
    PERFORM FIRST-TIME
ELSE
    MOVE DFHCOMMAREA TO WS-COMM
    PERFORM PROCESS-INPUT
END-IF.

PARM (EXEC statement):

• Limited to 100 characters
• Passed in memory to program
• Accessed via LINKAGE SECTION
• Good for small, simple parameters

SYSIN (DD statement):

• No practical size limit
• Read as a file by program
• Can contain multiple records
• Good for control cards, complex input

// PARM example
//STEP1 EXEC PGM=MYPROG,PARM='PARAM1,PARAM2'

// SYSIN example
//SYSIN DD *
CONTROL OPTION1
DATE=20231215
LIMIT=1000
/*

SQLCODE is a return code in SQLCA indicating the result of SQL execution.

Common SQLCODE values:

Negative = Error, 0 = Success, 100 = No data

COMMAREA (Communication Area) is used to pass data between programs or between transactions in pseudo-conversational programming.

Uses:

• Pass data between LINK/XCTL programs
• Save data between pseudo-conversational transactions
• Maximum size: 32KB

How it works:

1. Calling program: COMMAREA option on LINK/XCTL/RETURN
2. Called program: DFHCOMMAREA in LINKAGE SECTION
3. Check EIBCALEN for length (0 = no COMMAREA)

* Calling program
EXEC CICS LINK
    PROGRAM('SUBPROG')
    COMMAREA(WS-DATA)
    LENGTH(100)
END-EXEC.

* Called program
LINKAGE SECTION.
01 DFHCOMMAREA PIC X(100).

IF EIBCALEN > 0
    MOVE DFHCOMMAREA TO WS-DATA
END-IF.