extended interrupt screening table (XST)

A table that is initialized by the MVS SUPERVISOR PROGRAM with formatted information about the types of SVCs that it will process and its interrupt-handling (SPIH) routines for processing particular types of SVCs. Normally, one XST is created per SUPERVISOR PROGRAM. The XSTs for all active SUPERVISOR PROGRAMs are used by the Transport Mechanism’s DISPATCHER routine in the sequential calling of SUPERVISOR PROGRAMs in response to an SVC event. See alsosupervisor call (SVC).