Whereas a USERVAR is assigned to only one resource at a time, the generic resources function allows the assignment of a generic resource name to a group of active application programs that all provide the same function. The generic resource name is assigned to multiple active application programs simultaneously, and VTAM® automatically distributes sessions among these application programs rather than assigning all sessions to a single resource. Thus, session workloads in the network are balanced. Session distribution is transparent to users; an LU initiates a logon request using the generic resource name and need not be aware of which particular application program is actually providing the function.

The generic resources function also increases application program availability, as each active application program that uses a given generic resource name (a generic resource member) can back up other generic resource members. Thus, no single application program is critical to resource availability. When a generic resource member fails, an LU can reinitiate its session using the same generic resource name. VTAM resolves the session initiation to one of the other generic resource members. Because the user is unaware of which generic resource member is providing the function, the user is less affected by the failure of any single generic resource member.

In the same way, an application program can be added as a generic resource member and accessed using the same generic resource name. Because the user is unaware of which generic resource member is providing the function, an application program can be added as a generic resource member with little or no impact to the application user. At the same time, the additional application program provides an immediate improvement in performance and availability because the workload is now shared by an additional application program.

Use of generic resources requires a coupling facility structure. See Generic resources for additional information concerning generic resource requirements.