Use IXLLSTC REQUEST=MONITOR_LIST to monitor a list to determine whether its state is empty or not-empty. See Using Threshold Counts when Monitoring List State Transitions. For structures allocated in a coupling facility of CFLEVEL=9 or higher, the threshold counts that define the empty and not-empty state are specified with the IXLLSTC WRITE_LCONTROLS service. For structures allocated in a coupling facility of CFLEVEL=8 or lower, a list changes from the empty to the not-empty state when the list has no entries and an entry is created or moved to the list. A list changes from the not-empty to the empty state when the list has one entry and the entry is deleted or moved to another list.

MONITOR_LIST: Monitoring List Transitions describes the process of monitoring list transitions using the IXLLIST service. Processing list monitoring using IXLLSTC is comparable, with the only difference being that for structures allocated in a coupling facility of CFLEVEL=9 or higher, you can specify list empty and not-empty threshold counts.