If your program issues a macro that causes an asynchronous exit routine to run, that routine cannot use the DU-AL associated with your program. The system gives the routine an empty DU-AL for its own use and an EAX value of zero. The routine can use the PASN-AL associated with the primary address space.

Such asynchronous exit routines include those caused by the ATTACH macro with the ETXR parameter, the STIMER macro with the EXIT parameter, the SCHEDXIT macro, and some attention and I/O exit routines.

When control returns to your program from an asynchronous exit routine, the system deletes the DU-AL associated with the asynchronous routine and restores your program's DU-AL and EAX value.