Dynamic resource definition in an IMSplex

An IMSplex can include IMS systems that have DRD enabled and others that do not have DRD enabled. This kind of IMSplex environment is referred to as a mixed-DRD IMSplex.

If a command that contains the MODBLKS parameter is issued in a mixed-DRD IMSplex, the MODBLKS parameter is ignored.

Two scenarios are provided to demonstrate how to add application programs in a mixed-DRD IMSplex.

Scenario 1: add an application program to a mixed-DRD IMSplex

In this IMSplex, IMS1 has DRD enabled, and IMS2 and IMS3 do not have DRD enabled.

  1. Perform an ACBGEN for the PSB into the staging ACBLIB
  2. Perform a MODBLKS generation to define the APPLCTN program in the staging MODBLKS data set for the IMS2 and IMS3 systems.
  3. Create the application program dynamically by issuing the CREATE PGM command on the IMS1 or, if the program is to be scheduled in a BMP or JBP dependent region, by using the Program Creation user exit (PGMCREAT).
  4. Copy the staging MODBLKS data set and ACBLIB to the inactive MODBLKS data set and ACBLIB.
  5. Perform global online change for the MODBLKS data set and ACBLIB by issuing the following commands: 
    INITIATE OLC PHASE(PREPARE) TYPE(ACBLIB,MODBLKS)
INITIATE OLC PHASE(COMMIT)

The MODBLKS keyword is ignored by the IMS1 system; however, the IMSplex synchronizes and adds the program with one online change instance. The command that includes the MODBLKS keyword is not rejected; this would require another online change for the ACBLIB on the IMS1 system.

Scenario 2: add an application program and its MFS format in a mixed-DRD IMSplex that includes DBCTL IMS systems

IMS1 and DBCTL1 have DRD enabled. IMS2 and DBCTL2 do not have DRD enabled.

  1. Perform an ACBGEN for the PSB into the staging ACBLIB.
  2. Perform a MODBLKS generation to define the APPLCTN program in the staging MODBLKS data set for the IMS2 and DBCTL2 systems.
  3. Run the MFS utility to create an MFS format in the staging FMTLIB for the IMS1 and IMS2 systems.
  4. Create the application program dynamically by issuing the CREATE PGM command on the IMS1 and DBCTL1 systems or, if the program is to be scheduled in a BMP or JBP dependent region, by using the Program Creation user exit (PGMCREAT).
  5. Copy the staging MODBLKS data set and ACBLIB to the inactive MODBLKS data set and ACBLIB.
  6. Perform global online change for MODBLKS, FMTLIB, ACBLIB by issuing the following commands: 
    INITIATE OLC PHASE(PREPARE) TYPE(ACBLIB,FMTLIB,MODBLKS)
INITIATE OLC PHASE(COMMIT)

The MODBLKS keyword is ignored by the IMS1 and DBCTL1 systems. The FMTLIB keyword is ignored by the DBCTL1 and DBCTL2 systems. The ACBLIB keyword is processed on all four systems. This synchronizes the IMSplex and successfully adds the application program and its MFS format with one online change instance. The command that includes the MODBLKS keyword is not rejected; this would require additional online changes on IMS2, DBCTL1, and DBCTL2.

Related reading: For a detailed description of what you can do with DRD, see IMS Version 15.3 System Definition.