Operational considerations

Shared REGISET

You can restart a job step on a different MVS system than the system where the job step executed previously; however, both systems must use the same REGISET. You can use a different REGISET (and subsystem) on different MVS systems; using a different REGISET ensures that active job steps executing in one system are not confused with active job steps executing in another system. If two or more MVS systems are sharing a REGISET, ensure that one or more execution qualifiers distinguish job steps executing in a system from those executing in all other systems that share the REGISET.

Uncataloged data sets in STEPLIB

For an application program execution that uses AR/CTL, uncataloged or temporary data sets that are included in the STEPLIB concatenation are not supported. AR/CTL products are excluded from execution when the STEPLIB contains an uncataloged or temporary data set.

ABEND STEP processing

If you are using AR/CTL for VSAM and an application program is updating any VSAM files sequentially (deferred buffer writes), data integrity is compromised when the application task is canceled or abended with the STEP parameter of the ABEND macro in an Assembler language routine.

The STEP parameter causes all tasks in the job step to terminate abnormally. AR/CTL, as one of the tasks that abends, might not receive control to complete termination tasks and, therefore, can leave the active job step member in ACTIVE status. Before the job step can be restarted, you might need to reset the active job step member to ABENDED status.

Stop region and OS cancel commands

To avoid potential checkpoint-in-doubt situations, use the AR/CTL OCI STOP command rather than the IMS stop region command or the OS cancel command. AR/CTL maintains checkpoint control information to track the progress of the checkpoint process. At the beginning of the checkpoint process, AR/CTL updates this information to indicate that the checkpoint process has started. When the checkpoint process is complete, AR/CTL updates this information to indicate that the process is complete and to identify which checkpoint to use for restart. If an event (such as a power outage, an IMS stop region command, or an OS cancel) prevents AR/CTL from updating the checkpoint control information, a checkpoint- in-doubt situation can result, and you must manually determine which checkpoint to use for restart. If you use the OCI STOP command, AR/CTL is able to update the checkpoint control information and avoid the in-doubt situation.