Migrating from COMMAREAs to channels

CICS application programs that use traditional communications areas (COMMAREAs) to exchange data can continue to work as before. If you want to migrate to channels, here are examples of how to migrate several types of existing application to use channels and containers rather than COMMAREAs.

It is possible to replace a COMMAREA by a channel with a single container. While this may seem the simplest way to move from COMMAREAs to channels and containers, it is not good practice to do this. Because you're taking the time to change your application programs to exploit this new function, you should implement the best practices for channels and containers; see Designing a channel: Best practices. Channels have several advantages over COMMAREAs (see Benefits of channels ) and it pays to design your channels to make the most of these improvements.

Also, be aware that a channel may use more storage than a COMMAREA designed to pass the same data. (See Benefits of channels .)

User-written dynamic or distributed routing programs require work whether or not you plan to implement channels and containers in your own applications. If you employ a user-written dynamic or distributed routing program for workload management, rather than CICSPlex®  SM, you must modify your program to handle the new values that it may be passed in the DYRLEVEL, DYRTYPE, and DYRVER fields of the DFHDYPDS communications area. See Parameters passed to the dynamic routing program.