Control-O Usage of the Common Service Area (CSA and ECSA)

Control‑O receives control for processing events under the various tasks in the system, that is, Control‑O acts as part of the address space that issued the corresponding message, command, or other event. For that reason, some of the code and data that are in use by Control‑O reside in common storage, accessible from all address spaces, as outlined below. Most of this common storage is above the 16MB line, in the ECSA, but a small portion is allocated by Control‑O below the 16MB line, in the CSA, due to MVS services requirements.

Use the information in ECSA Usage (Above the 16 MB Line) and CSA Usage (Below the 16 MB Line) to calculate Control‑O ECSA and CSA storage requirements.