Your list transition exit provides a mechanism for list services to inform you that one or more lists and/or the event queue you are monitoring changed from empty to nonempty. The list transition exit parameter list (IXLYLEPL) does not specifically identify the affected monitored object, nor does it indicate how many monitored objects have transitioned. Your list transition exit must invoke the IXLVECTR macro to determine which monitored object(s) have changed from empty to nonempty.

You provide the address of your list transition exit using the LISTTRANEXIT parameter when you issue the IXLCONN macro to connect to the list structure. It is possible that your list transition exit might receive control before you receive control back from IXLCONN. Therefore, ensure that before you issue IXLCONN, you have the list transition exit established along with any control structures necessary to complete the exit's processing.

Design Considerations for Using the List Transition Exit discusses the list transition exit in more detail. This topic is limited to reference information for coding the exit.