CICS storage protection and transaction isolation

Storage control is affected by storage protection and transaction isolation. Storage protection protects CICS® code and control blocks from applications, and transaction isolation protects tasks from each other.

The subsystem storage protection facility enables you to prevent your application programs from accidentally overwriting CICS code and control blocks. It does not provide protection against deliberately overwriting CICS code or control blocks. CICS cannot prevent an application from obtaining the necessary access (execution key) to modify CICS storage.

Transaction isolation extends this storage protection to provide protection for transaction data. If an application program accidentally overwrites the transaction data of another transaction, it can affect the reliability and availability of your CICS system, and the integrity of the data in the system.

The use of storage protection is optional; you use CICS system initialization parameters to specify whether to use storage protection facilities. For information about the relevant parameters, see Storage protection.