CICS® recovery and restart facilities ensure that when the requesting transaction reaches a synchronization point, any mirror transactions that are updating recoverable resources also take a synchronization point, so that changes to recoverable resources in remote and local systems are consistent. The CICS master terminal (or, with CICS/400, the control region) receives notification of any failures in this process, so that suitable corrective action can be taken. This action can be taken manually or by user-written code.
When a transaction issues a synchronization point request, or terminates successfully, the intercommunication component sends a message to the mirror transaction that causes it also to issue a synchronization point request and terminate. The successful synchronization point by the mirror transaction is indicated in a response sent back to the requesting system, which then completes its synchronization point processing, so committing changes to any recoverable resources.