A control block used in the CALL DLI interface to pass information to the user program. It contains the address of the PCB address list (UIBPCBAL) from the schedule request, and the response code to each DL/I request. A definition of the UIB should only be included in the application program if the UIB is to be referenced. The UIB is acquired by the interface routine when an application program issues a schedule request specifying a pointer reference to be set with the address of the UIB.