Defining global online change

To enable global online change in an IMSplex that is defined with a CSL, the DFSCGxxx member or the CSL section of the DFSDFxxx member of the IMS PROCLIB data set must be specified.

The DFSCGxxx PROCLIB member and the CSL section of the DFSDFxxx PROCLIB member include parameters related to SCI, OM, and RM, which are common to all IMS systems in the IMSplex (except those systems defined without an RM). The OLC= parameter must specify GLOBAL for global online change or LOCAL for local online change.

OLC=GLOBAL means that the online change is coordinated across the IMSplex. Global online change is prepared and committed by the INITIATE OLC command. If global online change is enabled and a resource structure is defined, the MODBLKS, FORMAT, and ACBLIB data sets must be consistent across the IMSplex, unless resource consistency checking is omitted by the NORSCCC keyword.

OLC=LOCAL means the online change applies locally to each IMS. Local online change is prepared and committed by the/MODIFY PREPARE and /MODIFY COMMIT commands on each local IMS. The local online change must be manually coordinated across an IMSplex.

Specify the OLCSTAT data set using the OLCSTAT= parameter of the DFSCGxxx PROCLIB member data set or the CSL section of the DFSDFxxx PROCLIB member data set if global online change is enabled in an IMSplex with CSL. Run the Global Online Change utility (DFSUOLC0) to:

  • Initialize the OLCSTAT data set before IMS cold starts for the first time.
  • Recreate the OLCSTAT data set if an error makes the OLCSTAT data set unusable.
  • Unlock the OLCSTAT data set.