The purpose of the CICS-ICSF Attachment Facility is to enhance the performance of CICS transactions in the same region as a transaction using long-running ICSF services such as the PKA services and CKDS or PKDS update services.
Without the CICS-ICSF Attachment Facility, the application that requests a long-running ICSF service is placed into an OS WAIT. With the CICS-ICSF Attachment Facility, a long running service is transferred to an L8, and the CICS application is placed into a CICS WAIT, rather than an OS WAIT, for the duration of the operation.