After you have written CLISTs and executed them to make sure they run correctly, you can allocate them to special files to make them easier to execute.

When CLISTs are members of a partitioned data set (PDS) allocated to a special file, users and applications can execute the CLISTs implicitly by invoking the member names. How you can allocate CLIST libraries for implicit execution depends on the feature of TSO/E installed on your system.

The ALTLIB command gives you more flexibility in specifying CLIST libraries for implicit execution. With ALTLIB, a user or ISPF application can easily activate and deactivate CLIST libraries for implicit execution as the need arises. This flexibility can result in less search time when fewer CLISTs are activated for implicit execution at the same time.

In addition to CLISTs, the ALTLIB command lets you specify libraries of REXX execs for implicit execution. For information about using ALTLIB with REXX execs, see z/OS TSO/E REXX User's Guide.