The 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 logon post-display exit receives control only if the logon pre-prompt exit (IKJEFLD/IKJEFLD1) does not set the "Don't Prompt" control bit. TSO/E can invoke the logon post-display exit several times on each invocation of the LOGON command.