The first RB that issues an ASYNC EZASMI call under a given task is deemed as the target RB that is interrupted when an asynchronous exit needs to be driven. This means that after an asynchronous EZASMI macro call is invoked you should not invoke any services that cause the current RB to no longer be the top RB for this task (for example, a LINK call). If the target RB is no longer the top RB at the time that the exit needs to be driven, then the exit is deferred until the target RB becomes the top RB. One exception to this rule is that EZASMI calls can be issued under the asynchronous user exit.

While running the asynchronous exit notification routine, an application can issue other EZASMI calls. However, the application should avoid issuing any blocking calls and should not enter into long delays. Doing so delays any additional exits from being driven and also blocks the TCB that made the original call. Note that TERMAPI should not be issued under the asynchronous exit.

Applications issuing EZASMI macro asynchronous exit calls should not issue any PC instructions that cause the system linkage to be used. Doing so delays the asynchronous exits from being driven until the linkage stack entry is removed. If the linkage stack entry is not removed, the exit will not be driven.