Defining GRS Resource Names for SMS Control Data Sets

As you prepare to allocate the SMS control data sets, consider the effects of multiple systems sharing these data sets.

Between systems, the data sets are serialized by RESERVE/RELEASE. If you allocate a data set on a device with other data sets protected by RESERVE/RELEASE, it locks out all activity from other systems to that volume.

Recommendation: Ensure that you use global resource serialization (GRS) to convert the reserve into a global ENQ.

A reserve is issued while updating the control data sets for the following reasons:

The COMMDS is updated with space statistics at the expiration of the time interval specified in the IGDSMSxx member in PARMLIB.
The ACDS is updated whenever a configuration change occurs, such as when an operator varies a volume offline.

You should place resource name IGDCDSXS in the RESERVE conversion RNL as a generic entry. This minimizes delays due to contention for resources and prevents deadlocks associated with the VARY SMS command.

Make sure to convert the RESERVEs to global ENQs. Using RESERVE/RELEASE can result in deadlocks even if the COMMDS and ACDS data sets are the only ones on separate volumes.

Requirement: If you have multiple SMS complexes within a global resource serialization complex, be sure to use unique COMMDS and ACDS data set names to prevent false contention.