Status change call-back capability

Sometimes the User Control exit needs to modify its operating environment or disable itself altogether.

A special call-back facility is provided to enable these changes during any User Control exit call. For example, if the User Control exit determines that it should decrease the scope of exit routine serialization from the system-level default (allowing one active caller from a single address space) to a step-level (allowing one active caller from a number of address spaces), or to disable serialization altogether (allowing a number of active callers from a number of address spaces), the appropriate bits in the DEPLSCFLAGS field are set and the routine whose address is contained in DEPLSCENTRY is called to perform the change. When control is returned from the call-back facility, the status change is in effect.

Note

The serialization change in the preceding example might typically be performed during the exit initialization call if the User Control exit can support concurrent callers from multiple address spaces. The sample exit routine contains this type of logic.

Related topic

Implementing User Control exit

Status change call-back capability

Comments