Using IMS application program sync points

IMS application programs can (and should) take checkpoints. These checkpoints and system sync points can affect IMS operations.

Commit process
During the synchronization point (sync point) processing for an application, IMS creates a log record to establish commitment of database changes and availability of output messages. The commit process is not complete until IMS physically writes this log record to the OLDS because an incomplete set of database change and message records exist on the log for system restart.
Two-phase commit in the synchronization process
Application programs in a DBCTL, DCCTL, DB/DC, APPC/IMS, or OTMA environment can be involved in a two-phase commit process to record a sync point. At the completion of a two-phase commit, the resource manager commits database and message changes.
Sync-point log records
During the two-phase commit process, IMS creates log records to establish the commitment of database changes. All these log records can be used by the IMS Change Accumulation and recovery utilities.
Sync points with a data-propagation manager
When using a data-propagation manager (such as the IMS DataPropagator) to update Db2 for z/OS® databases synchronously with IMS DL/I databases, the updates to the Db2 for z/OS databases are committed (or aborted) at the same time as the IMS updates. This provides consistency between the database management subsystems. IMS DB/DC, DCCTL, and DBCTL (BMP regions only) support the IMS Data Capture exit routine.

Parent topic: Application programming for IMS DB