CICS Modernization

CICS modernization means connecting trusted CICS applications to new technology without rewriting them. Small changes can expose decades of business logic as modern APIs.

Channels and containers

• Channels and containers replace the COMMAREA for passing data between programs.
• A COMMAREA is limited to 32 KB. Containers can hold megabytes of data.
• A channel holds many named containers, so programs can pass several separate data areas at once.
• New programs should use channels. Convert COMMAREA programs when you touch them for other changes.

Ways to modernize

• Expose COBOL logic as JSON or SOAP web services with the CICS web services support.
• Use z/OS Connect to create REST APIs from existing COBOL programs with no program changes.
• Run Java in CICS with a Liberty JVM server for new components that live next to COBOL.
• Manage many regions with CICSPlex SM and develop with the CICS Explorer instead of green screens.
• Use CICS event processing to emit business events to analytics systems without changing program logic.

Example: passing data with a channel

• PUT the data into a named container, then LINK to the program with the channel.
• WORKING-STORAGE SECTION. 01 WS-ORDER-REC PIC X(200). 01 WS-RESPONSE PIC S9(8) COMP. PROCEDURE DIVISION. EXEC CICS PUT CONTAINER('ORDER-DATA') CHANNEL('ORDER-CHAN') FROM(WS-ORDER-REC) FLENGTH(LENGTH OF WS-ORDER-REC) END-EXEC. EXEC CICS LINK PROGRAM('ORDRPROC') CHANNEL('ORDER-CHAN') RESP(WS-RESPONSE) END-EXEC.
• The called program reads the container with EXEC CICS GET CONTAINER using the same channel and container names.
• Containers disappear when the task ends unless you make them persistent, so pass only what the next program needs.