How does VTAM on an APPN end node register the generic resource name of an application it owns to the end node's network node server?

Each VTAM application in a sysplex that supports generic resources, for example, CICS, has to register itself under its generic resource name via the VTAM API macroinstruction SETLOGON OPTCD=GNAMEADD. To deregister, it would issue the VTAM API macroinstruction SETLOGON OPTCD=GNAMEDEL.

When VTAM processes the SETLOGON call, it stores the details of this application in the ISTGENERIC structure. The structure would contain

• the generic resource group name

• the real name of the application

• the CP name of the owning VTAM.

In order for the NNS of the VTAM ENs that own the generic resource to be aware of the generic resource, the NNS should belong to the same sysplex as the ENs and connect to the same generic resource structure. If the NNS resides outside the sysplex, then you need to code the ENBCAST operand on the NETSRVR statement in the EN's NETSRVR list.

This is only recommended for a backup NNS, due to performance reasons.

As per the CS:SNA Network Implementation Guide, section: 16.3.1 Generic resources requirements ... A network node server is required to provide generic resource resolution for resources on end nodes within the generic resource configuration.

The recommended APPN generic resource configuration consists of a network node and served end nodes connected to the same generic resource structure with a backup network node connected to the same structure.

But a backup network node server that is not connected to the same generic resource structure can be used. This requires that the end nodes allow broadcast searches, by coding ENBCAST=YES on the backup network node server entry in the end node's NETSRVR list. Refer to the ENBCAST operand on the NETSRVR statement for the VTAMLST VBUILD TYPE=NETSRVR list in z/OS Communications Server: SNA Resource Definition Reference.