Preventing duplicate writes during CICS transaction retries

In a COBOL application running under CICS, maintaining data integrity during transaction retries is critical. While the use of sync-points and the EXEC CICS SYNCPOINT command ensures that a Logical Unit of Work (LUW) is processed atomically, the system does not natively track whether a specific business event has already been persisted if the transaction is restarted from an external trigger.

When a transaction fails after a partial write but before a final commit, the transaction manager handles the rollback. However, if the retry logic is initiated by an external system or a user, there is a risk of duplicating records if the previous attempt partially succeeded in a way that bypassed the sync-point or if the retry occurs after a successful commit but before the confirmation is received.

What are the established patterns for implementing idempotency within COBOL to ensure that retried transactions do not create duplicate entries in the database? Which mechanism is more reliable for verifying record existence before a write operation in high-volume CICS environments?