Initializing system data sets when not using online change

If you do not plan to use the online change function, you do not need to maintain the full set of staging, active, and inactive libraries. You need to manage only the staging libraries. You do not need to make copies for the active data sets, which would have the same contents.

You need to modify the JCL, generated in the IMS member of the IMS PROCLIB data set, for the online execution for the following ddnames:

  • MODBLKSA
  • MODBLKSB
  • IMSACBA
  • IMSACBB
  • FORMATA
  • FORMATB

Procedure

  1. For each of these DD statements, use a DSN parameter pointing to a staging library.
    For example, ddnames MODBLKSA and MODBLKSB use DSN=IMS.MODBLKS, and ddnames FORMATA and FORMATB use DSN=IMS.FORMAT. If you plan to use terminals in MFSTEST mode, the DD statements for the MFS library that contain the formats under test (ddnames IMSTFMTA and IMSTFMTB) have the staging library (IMS.FORMAT) concatenated to IMS.TFORMAT.
  2. Initialize either the IMS.MODSTAT or IMSPLEX.OLCSTAT data set:
    1. If global online change is not enabled, initialize the IMS.MODSTAT data set appropriately, which is most conveniently done using the INITMOD procedure.
      This procedure initializes IMS.MODSTAT so that the ddnames with suffix A are set to be the active libraries.
    2. If global online change is enabled, initialize the IMSPLEX.OLCSTAT data set instead of the IMS.MODSTAT data set.
      When creating and allocating the OLCSTAT data set, make sure that an End of File (EOF) mark is placed at the beginning of the data set. Failure to do so can produce unpredictable results. To place an EOF mark at the beginning of the data set, use program IEBGENER. Do not use program IEFBR14 to allocate the OLCSTAT data set. IEFBR14 does not place an EOF mark at the start of the data set. An alternate method of allocating the OLCSTAT data set is to use the ALLOCATE function of ISPF utilities. The ALLOCATE function places an EOF mark correctly at the beginning of the data set.