Application sync points

IMS system checkpoints help you recover the IMS subsystem, but you also need to be able to restart application programs if they fail. IMS allows application programs, both batch and online, to take sync points.

An application program sync point has two purposes:

It marks an intermediate completion point—a place at which the work finished so far is judged to be correct. Any future recovery can take place from this point.
It frees locks held on database records the program has updated and enqueues any output messages the program created. IMS can send enqueued messages to their destinations.

Application program sync points are sometimes called commit points. By taking a sync point, the program is committing itself to the accuracy and completeness of what it has done, and releasing the data for use by other applications.