The common work area (CWA) is a single control block that is allocated at system startup time and exists for the duration of that CICS session. The size is fixed, as specified in the system initialization parameter, WRKAREA. The CWA has the following characteristics:
There is almost no overhead in storing or retrieving data from the CWA. Command-level programs must issue one ADDRESS command to get the address of the area but, after that, they can access it directly.
Data in the CWA is not recovered if a transaction or the system fails.
It is not subject to resource security.
CICS does not regulate use of the CWA. All programs in all applications that use the CWA must follow the same rules for shared use. These are usually set down by the system programmers, in cooperation with application developers, and require all programs to use the same "copy" module to describe the layout of the area.
You must not exceed the length of the CWA, because this causes a storage violation. Furthermore, you must ensure that the data used in one transaction does not overlay data used in another. One way to protect CWA data is to use the storage protection facility that protects the CWA from being written to by user-key applications.
The CWA is especially suitable for small amounts of data, such as status information, that are read or updated frequently by multiple programs in an application.
The CWA is not suitable for large-volume or short-lived data because it is always allocated.