VTAM Generic Resources (VGR) and MSC

MSC IMS systems outside of an IMSplex can use a VTAM® generic resource group name (GRSNAME) to establish MSC link sessions with the IMSplex instead of using the APPLID of a specific IMS system in the IMSplex.

When you use a VTAM GRSNAME, you can move MSC link sessions between IMS systems within the IMSplex without having to change the VTAM node name on the NAME parameter of the CREATE MSPLINK command or in the MSPLINK stage 1 system definition macro for each IMS system outside the IMSplex.

Using a VTAM GRSNAME can also make cloning IMS systems within an IMSplex easier because the same MSC link definition can be used by each IMS system within the IMSplex to connect to a remote IMS system. Each parallel link in the IMSplex can use a common GRSNAME to establish a session with an IMS system outside of the IMSplex. Other link attributes, such as partner ID, SYSIDs, and so forth, can also be cloned across the IMS systems within an IMSplex.

The use of VTAM generic resources in an IMSplex is transparent to the external MSC system. The external MSC system need only specify the GRSNAME that is used by the IMSplex, instead of a specific IMS system APPLID name, on the NAME parameter of the CREATE MSPLINK command or the MSPLINK macro. In the IMSplex, the MSC VGR support is enabled by specifying MSCVGR=Y (MSCVGR=N is the default) in the DFSDCxxx PROCLIB member of each IMS system in the IMSplex. The IMSplex must also have VTAM generic resources enabled.

When MSC VGR support is enabled, also specify GRMESTAE=Y (the default) in the DFSDCxxx PROCLIB member to ensure that IMS deletes VTAM affinity if an IMS abend should occur. The type-1 command /DISPLAY AFFIN LINK and the type-2 command QUERY MSLINK SHOW(AFFIN) display current affinities between MSC links and the IMS systems in an IMSplex.