Enabling the global online change function

Use the Global Online Change utility (DFSUOLC) to initialize the OLCSTAT data set and enable an IMSplex for global online change.

To enable an IMSplex for global online change, you must:

Procedure

  1. Run the Global Online Change utility (DFSUOLC0) to initialize the OLCSTAT data set.

    The Global Online Change utility needs to be run once before the first IMS cold starts the first time. The OLCSTAT data set is comparable to the MODSTAT data set used by local online change.

    Important:
    • Use the Global Online Change utility with caution, so you do not inadvertently destroy valid OLCSTAT data set contents. If you do destroy valid OLCSTAT data set contents, global online change and initialization of additional IMS systems fail until the OLCSTAT data set is re-initialized.

      You should establish an OLCSTAT data set recovery procedure to deal with the loss of the OLCSTAT data set. After every successful global online change, record the modify ID, the active online change library suffixes, and the list of IMS systems that are current with the online change libraries. If the OLCSTAT data set is destroyed, run the initialize function of the Global Online Change utility with the saved data to re-initialize the OLCSTAT data set.

      Related reading:  For more information about the Global Online Change utility, see IMS Version 15.3 System Utilities.

    • If you build a multisystem sysplex, you automatically build a global resource serialization complex with it. Global online change relies on global resource serialization to serialize access to the OLCSTAT data set from multiple systems. If you use global online change in a sysplex with more than one z/OS® system, you should not define the GRSRNL=EXCLUDE parameter in the MVS parmlib. Defining GRSRNL=EXCLUDE makes the OLCSTAT data set serialization local instead of global.
    • For an IMSplex running without an RM (with CSL global parameters RMENV=N and OLC=GLOBAL), you must ensure that another IMS subsystem does not attempt to use the OLCSTAT data set from the IMS subsystem that is running without RM.
  2. For each IMS in the IMSplex, perform these steps:
    1. Remove the MODSTAT DD and MODSTAT2 DD statements from the IMS control region JCL.
    2. Define DFSCGxxx IMS.PROCLIB member parameters related to global online change, or in the CG section of DFSDFxxx member.

      Specify OLC=GLOBAL to enable global online change.

      Specify OLCSTAT= with the online change status data set name. All of the IMS systems in the IMSplex must specify the same OLCSTAT data set.

    3. Shut down IMS.
    4. Cold start the IMS.