TCL SYNCPOINT
The SYNCPOINT
statement is used in mainframe environments,
particularly in transactional applications using CICS (Customer Information Control System).
It functions similarly to a COMMIT
statement but also manages transactions across multiple resources.
SYNCPOINT ensures all changes are made permanent and other resources like files or queues,
maintaining data integrity in complex applications involving DB2 and CICS.
In mainframe environments, the SYNCPOINT
statement commits all changes made during a transaction to multiple resources,
such as DB2 tables, VSAM files, and other CICS-managed resources. It is essential for:
- Finalizing transactions across different resources in a single operation.
- Ensuring data consistency across multiple resources by committing all changes or none.
Without SYNCPOINT, changes across resources may not be coordinated, leading to data inconsistencies in applications requiring multi-resource transactions.
Syntax -
SYNCPOINT;
- SYNCPOINT: Commits changes across all resources in the transaction.
- SYNCPOINT ROLLBACK: Reverts changes across all resources, effectively canceling the transaction.
Using SYNCPOINT Statement in a COBOL Program
In a COBOL-CICS program, SYNCPOINT
is used after completing all operations to be committed.
Executing SYNCPOINT
finalizes changes across resources, ensuring data consistency.
It is especially useful in applications where DB2 tables, VSAM files, and message queues are updated in a coordinated manner.
General Steps for Using SYNCPOINT in a COBOL-CICS Program:
- EXEC CICS: Begin with the EXEC CICS block.
- SYNCPOINT: Place
SYNCPOINT
after data modification statements across different resources. - Error Handling: Check
EIBRESP
(CICS response code) to confirm successful SYNCPOINT execution.
Examples - SYNCPOINT Statement in a COBOL-CICS Program
* Step 1: Update Data in DB2 Table EXEC SQL UPDATE EMPLOYEE SET SALARY = SALARY + 1000 WHERE JOB = 'MANAGER' END-EXEC. ... * Step 2: Write Data to VSAM File EXEC CICS WRITE FILE('VSAMFILE') FROM(WS-DATA-RECORD) RESP(EIBRESP) END-EXEC. ... * Step 3: Commit Transaction Across Resources EXEC CICS SYNCPOINT END-EXEC.
Error Handling for the SYNCPOINT Statement in a COBOL Program
In a COBOL-CICS program, error handling for the SYNCPOINT statement involves checking EIBRESP
after execution:
- EIBRESP = 0: SYNCPOINT executed successfully, and changes are committed across all resources.
- EIBRESP < 0: Indicates an error, meaning the transaction was not committed. This may require retrying the transaction or performing a rollback.
Examples - Error Handling with SYNCPOINT Statement
EXEC CICS SYNCPOINT END-EXEC. IF EIBRESP = 0 DISPLAY 'Transaction committed successfully.' ELSE DISPLAY 'Error in SYNCPOINT operation: ' EIBRESP END-IF STOP RUN.