Dynamic resource definition and system definition

Specify parameters related to dynamic resource definition (DRD) in the DFSDFxxx member of the IMS PROCLIB data set.

The DFSDFxxx member of the IMS PROCLIB data set contains parameters for the IMS Common Service Layer (CSL), shared queues, databases, restart exit routines, dynamic resource definition (DRD), the IMSRSC repository, dynamic database buffer pools, the Fast Path 64-bit buffer manager, and the IMS abend search and notification procedure.

The DFSDFxxx member includes some parameters that also exist in the DFSSQxxx member (for defining parameters related to shared queues) and the DFSCGxxx member (for defining parameters related to the CSL). If you specify these common parameters in the DFSDFxxx member, you do not have to specify them in the DFSSQxxx and DFSCGxxx members. Any attributes explicitly defined in the DFSSQxxx and DFSCGxxx members override the attributes defined in the DFSDFxxx member.

The MODBLKS= keyword enables either DRD (MODBLKS=DYN) or the online change process (MODBLKS=OLC). The MODBLKS= keyword can only be changed as part of a cold start. MODBLKS=OLC and MODBLKS=DYN are mutually exclusive. You can specify the MODBLKS= keyword in either the DFSCGxxx member, or in the CSL section of the DFSDFxxx member. If you specify a value for the MODBLKS= keyword in the DFSCGxxx member, that value overrides the value specified for the MODBLKS= keyword in the DFSDFxxx member.

If the online change process is disabled (DRD is enabled), the IMS, DBC, and DCC procedures no longer require the DD statements for the IMS.MODBLKS data sets, IMS.MODBLKSA and IMS.MODBLKSB.

The DFSDFxxx member of the IMS PROCLIB data set contains the MSC section, which specifies options for the Multiple Systems Coupling function, including DRD support.