Defining connections in a generic resource environment

The VTAM® generic resource function can be used to balance session workload for APPC and LUTYPE6.1 connections. Connections differ from terminal sessions in the following ways:

Defining connections

When you define a connection to a generic resource, you have two possibilities for the NETNAME option of DEFINE CONNECTION:

  1. Use the name (applid) of the generic resource member. This type of connection is known as a member name connection.
  2. Use the name of the generic resource. This type of connection is known as a generic resource name connection.

It is important that you make the correct choice when you define connections to a generic resource:

When a CICS Transaction Server for z/OS® generic resource member sends a BIND request on a connection, the request contains the generic resource name and the member name of the sender. If the partner is also a CICS TS z/OS generic resource, it can distinguish both names. Other CICS systems take the generic resource name from the bind, and attempt to match it with a connection definition.

It follows that the only time an LUtype 6 which is not itself a member of a CICS TS z/OS generic resource can successfully use a member name to connect to a generic resource is when the generic resource member will never initiate any sessions. This is an unusual situation, and we therefore recommend that a connection from a system that is not a CICS TS z/OS generic resource member to a generic resource should use the generic resource name.

Defining connections between GR members and non-GR members

When a generic resource member initiates a connection (that is, sends the first BIND) to another LUtype 6, it identifies itself to its partner with its generic resource name. Sessions initiated by the partner must then also use the generic resource name of the LU that initiates the connection.

Defining connections between members within a generic resource

You may want to define connections between members of a generic resource. You should always specify, on the NETNAME option of these CONNECTION definitions, the partner’s member name and not the generic resource name.

Defining connections between CICS TS z/OS generic resources

If you have two CICS TS z/OS generic resources, you do not need to define and install member name connections for every possible connection between them. Instead, you can define and install a single generic resource name connection in each member that may initiate a connection with the partner generic resource. CICS then autoinstalls member name connections as they are required.

The only connection definition required in a CICS region that does not initiate connections is one that can be used as an autoinstall template. If there is a generic resource name connection installed, it is used as the template, so we suggest that you define generic resource name connections for this purpose.

Related tasks
Planning your CICSplex to use VTAM generic resources
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
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