Additional storage is used when processing APPC/MVS work. APPC/MVS requires storage for message buffers, internal control blocks, and in-storage copies of the TP profiles and side information. These storage structures are allocated in the APPC and ASCH address spaces, and additional data is kept in the MASTER address space. These three address spaces need 1-2 megabytes to start and run one of the sample transaction programs supplied with APPC/MVS. Executing a low rate of APPC/MVS transaction programs requires approximately 3 megabytes of processor storage in these address spaces. A large mainframe processor, such as an IBM® 3090/300J executing only APPC/MVS transaction programs, requires approximately 12 megabytes of processor storage for the APPC and ASCH address spaces and the additional data kept in the MASTER address space. In all cases, you must also include the processor storage that the transaction programs require.

Idle APPC/MVS transaction initiators have approximately the same storage requirements as JES initiators. When these initiators are executing an APPC transaction program, the storage requirements depend on the requirements of the application.

Because of its need for increased processor storage, APPC/MVS may require additional auxiliary storage and paging space. For information about buffer storage limits, which is related to paging requirements, see Controlling Buffer Limit Size.