PST= parameter for procedures

Specifies the number of partition specification tables (PSTs) to be allocated during system initialization. This number can be between 0 and the number specified on the MAXPST= control region parameter. The default is 0.

Each active dependent region, DBCTL thread, or ODBA thread uses a PST. If additional dependent regions or threads are required during peak periods, IMS dynamically allocates additional PSTs as the dependent regions or threads are started. PSTs can be allocated up to the MAXPST value.

During idle periods, the PSTs are released. The number of PSTs specified on PST= is maintained. For example, if PST=15, it is assumed that approximately 15 dependent regions or threads are always active. During peak periods, if additional dependent regions or threads are started, IMS dynamically allocates a PST for each dependent region or thread, up to the MAXPST value. As PSTs are terminated, the PSTs are released until a value of 15 PSTs is reached. This support is within the constraints of the operating system or subsystem being used.