Scheduling Exits in Other Tasks

An authorized program can schedule an exit for any task in any group machine. With the SCHEDEX macro, the program can preempt a specific task and arrange for a designated exit routine to assume control. Instead of the task getting dispatched (if it is not disabled), the exit routine gets control in supervisor state and with a PSW key of 0.

After scheduling the exit, the authorized program continues executing. And after the exit routine finishes, GCS lets the interrupted task continue executing.