Shared storage is allocated by a GETMAIN SHARED command, and remains allocated until explicitly freed by the same, or by a different, task.
Shared storage can be used to exchange data between any CICS tasks that run during the lifetime of the shared storage. Transactions designed in this way must execute in the same CICS region to work correctly. The dynamic or distributed routing program should ensure that transactions using shared storage are routed to the same target region.
If the two transactions shown in Figure 1 are parts of a pseudoconversational transaction, the use of shared storage should be replaced by a COMMAREA (if the amount of storage fits within the COMMAREA size limits).