When signals cannot be delivered

Compilers and applications that enter states when signals cannot be delivered should invoke z/OS UNIX callable services after returning to a state where signal delivery is possible. This action ensures prompt delivery of signals. For example, a program may invoke a STORAGE obtain and getpid service. After returning from the getpid service, z/OS UNIX delivers any asynchronous signals that were generated during the STORAGE obtain.

When the SIR is unable to deliver a signal to a signal catcher routine for environmental reasons, the queue_interrupt service is invoked from a signal interface routine (SIR). The queue_interrupt service also delays signal delivery until the next z/OS UNIX callable service. z/OS UNIX callable services should be performed shortly after a queue_interrupt call to ensure prompt signal delivery.