CA-MIM resource sharing

TDMF periodically issues a reserve macro (TDMFRESV) to the volume where the Communications data set (COMMDS) is resident. Dependent on how certain parameters are set within Multi-image Manager (MIM), this could cause the reserve to be converted by MIM to a global enqueue.

Important: It is recommended that the physical device reserve mechanism be used to ensure serialization of the Communications Data Set. In situations when the volumes suitable for the Communications Data Set are shared across sysplexes and must not be physically reserved, the TDMFRESV resource can be converted by CA-MIM and propagated to the Agent systems using GDIF.

The following procedure helps determine what actions need to be taken to avoid this reserve conversion. This information has been supplied courtesy of CA-MIM Technical Support.

  1. Go into the MIMINIT deck and search for PROCESS=

    The options available are SELECT or ALLSYSTEMS. The differences between these two options are described as follows:

    • PROCESS=SELECT tells MIM to only manage and convert the enqueues and reserves that are indicated in the MIMQNAMES list and GDIEXMPT list.
    • PROCESS=ALLSYSTEMS directs MIM to manage all enqueues and reserves that have a SCOPE=SYSTEMS unless the qname is specified in the MIMQNAMES list with GDIF=NO, or the data set is specified in the GDIEXMPT list via a LOCAL statement.
  2. To prevent MIM from converting the RESERVE to a global enqueue for the COMMDS data set, do one of the following:
    • If running with GDIINIT PROCESS=SELECT:

      Do not define the TDMFRESV qname to MIM via the MIMQNAME member.

    • If running with GDIINIT PROCESS=ALLSYSTEMS:

      Define the following to the MIMQNAME member

      TDMFRESV GDIF=NO

If assistance is required to code the MIM parameters, contact CA-MIM Technical Support. Multi-image Manager (MIM) release 4.1 and above supports four (4) digit UCBs. Support for UCBs above the 16-MB line for disk and tape is available at maintenance level 9608. Support for CTC UCBs above the 16-MB line is available at maintenance level 9706.

For those customers using GRS, refer to Coexistence with EMC’s z/OS migrator.