Planning your CICSplex to use VTAM generic resources

You can use the VTAM® generic resource function to balance terminal session workload across a number of CICS® regions. You do this by grouping the CICS regions into a single generic resource. Each region is a member of the generic resource. When a terminal user logs on using the name of the generic resource (the generic resource name), VTAM establishes a session between the terminal and one of the members, depending upon the session workload at the time. The terminal user is unaware of which member he or she is connected to. It is also possible for a terminal user to log on using the name of a generic resource member (a member name), in which case the terminal is connected to the named member.

APPC and LUTYPE6.1 connections do not log on in the same way as terminals. But they too can establish a connection to a generic resource by using either the generic resource name (in which case VTAM chooses the member to which the connection is made) or the member name (in which case the connection is made to the named member).

When you plan your CICSplex to use VTAM generic resources, you need to consider the following:

Naming the CICS regions

Every CICS region has a network name, defined on a VTAM APPL statement, that uniquely identifies it to VTAM. You specify this name, or applid, on the APPLID system initialization parameter. If a region is a member of a generic resource, its applid and member name are one and the same.

A generic resource--a collection of CICS regions--has a generic resource name. Each CICS region that is to be a member of a generic resource specifies the generic resource name on its GRNAME system initialization parameter. Unlike network names, generic resource names do not have to be defined to VTAM. However, they must be distinct from network names, and must be unique within a network. The System/390 MVS Sysplex Application Migration manual suggests naming conventions for CICS generic resources.

When you start to use generic resources, you must decide how the generic resource name and the member names are to relate to the applids by which the member regions were known previously:

Generic resources and XRF

Because you cannot use XRF with VTAM generic resources, the concept of "specific" and "generic" CICS applids is not meaningful to regions that are members of a generic resource group. Each generic resource member has only one applid.

For a full explanation of the relationships between generic and specific CICS applids, VTAM APPL statements, and VTAM generic resource names, see Generic and specific applids for XRF.

Related tasks
Defining connections in a generic resource environment
Generating VTAM generic resource support
Migrating a TOR to a generic resource
Removing a TOR from a generic resource
Moving a TOR to a different generic resource
Setting up inter-sysplex communications between generic resources
Ending affinities
Using ATI with generic resources
Using the ISSUE PASS command
Dealing with special cases
Related reference
Prerequisites for VTAM generic resources
Rules checklist

10.
You are recommended to use APPC in preference to LUTYPE6.1 for CICS-to-CICS connections.
11.
You cannot use LUTYPE6.1 connections between members of a generic resource.

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