The CLIST statement exit must follow standard linkage conventions. It must save the registers on entry and restore the registers when it returns. The exit must be reentrant, refreshable and reusable.

The exit must determine whether the statement should be treated as an installation-written CLIST statement or as a TSO/E command. If the statement is defined by the installation, the exit must perform the necessary processing. Otherwise, the installation must indicate that the statement is a TSO/E command, by setting a return code of 0.

The exit can use the variable access routine (IKJCT441) to update, create and retrieve the value of REXX and CLIST variables. For information on how to use IKJCT441, see .