Determining when affinities are terminated

When you terminate a session by logging off, IMS terminates the affinity between your node and the IMS VTAM® generic resource member. However, in some situations, affinities persist.

You can use several methods in order to terminate these affinities.

Affinity for MSC and ISC parallel sessions is maintained as long as one or more sessions are active, or at least one session has significant status and the recovery mode is local. MSC sessions terminate the VTAM affinity when a /PSTOP LINK command is issued for all parallel link sessions. MSC recovery mode is always local.

ISC sessions terminate the VTAM affinity when:

• A /QUIESCE NODE command is issued (cold termination) for all sessions and recovery mode is local or global.
• A /CLOSE NODE command is issued (warm termination) for all parallel sessions and the recovery mode is global.

The VTAM affinity is also terminated when IMS is shut down normally by a /CHE FREEZE|PURGE|DUMPQ command and all sessions are successfully terminated. The /CHE FREEZE|PURGE|DUMPQ LEAVEGR command terminates all affinity unconditionally. Whether the shutdown is initiated by IMS (/CHE) or by the session (/PSTOP, /CLOSE, or /QUIESCE), the affinity is maintained if any parallel MSC or ISC sessions between the same IMS systems remain active or have been terminated but still have a significant status.

If there are parallel sessions using both MSC and ISC between the same IMS systems, then the previously mentioned affinity rules are applied simultaneously. That is, the affinity is maintained for both MSC and ISC parallel sessions if any link or node has significant status.

In order for IMS to terminate the affinity in all cases, the VTAM ACB must be opened with a /START DC command.

MSC significant status (MSC recovery mode is always local)

• Link is in active status
• Link is in ERE status

ISC significant status

• Node is in active status
• Node is using RM local recovery mode (SRMDEF=Local for the node) and is in warm terminate status

To display the list of IMS systems and their affinities with specific nodes or MSC links, use the /DISPLAY AFFIN command.

Related reading: For information on the /DISPLAY AFFIN NODE or /DISPLAY AFFIN LINK command, see IMS Version 15.3 Commands, Volume 1: IMS Commands A-M.

For information on how to terminate affinities that persist, see Terminating affinities that persist.