User interface block (UIB)

The user interface block (UIB) is the control block used by the CALL and CALL DL/I interfaces to pass response codes and the PCB address list to application programs using CALL DL/I services. The UIB is acquired when a task issues its first PSB schedule request specifying that it requires a UIB. The UIB is freed at task termination. TCADLIBA points to the UIB.

See Data areas for a detailed description of these control blocks.