Serializing access to resources through the ISGENQ macro

IBM® recommends using ISGENQ RESERVEVOLUME=NO, but you can also use ISGENQ RESERVEVOLUME=YES or the RESERVE macro to serialize access when the following is true:

The resource needs to be shared outside of the GRS complex. See z/OS MVS Planning: Global Resource Serialization for more information about GRS Complexes and the use of RESERVE.
Your installation is not using SMS to manage the shared data sets.

Obtaining a reserve increases the probability of contention for resources and the possibility of interlocks. If you use a reserve to serialize access to data sets on shared DASD, use ISGENQ REQUEST=RELEASE or the DEQ macro to release the resource.

When different systems in your installation access data sets on shared DASD, you can specify the keyword RESERVEVOLUME=YES with a scope of SYSTEMS or SYSPLEX on the ISGENQ macro to serialize access to those resources. That is, RESERVEVOLUME=YES is used when a hardware reserve is required to allow global resource serialization to share a DASD volume outside of the complex.