CICS
The transaction manager that runs online mainframe applications, and the software behind a great many screens bank staff use.
Also written Customer Information Control System, CICS TS
CICS, or Customer Information Control System, is the environment online transactions run in. Where batch jobs process files in bulk, CICS handles short pieces of work triggered by someone at a screen or by another system, and it handles enormous numbers of them at once.
It takes care of everything around the application: receiving the request, finding and starting the right program, managing the screen, handling access to files and databases, coordinating changes so they either all commit or all back out, and handling security. The application program itself concentrates on the business logic and asks CICS for services through commands.
It is startlingly efficient. A single CICS region can serve thousands of concurrent users because programs are shared and each transaction occupies resources only for the fraction of a second it is actually running.
Modern CICS is not restricted to green screens. The same application logic can be reached through web services and APIs, which is how a mobile banking app often ends up calling a transaction written decades ago.
Related terms
- CICS transactionOne unit of online work in CICS: the whole exchange of receiving a request, doing the work, and sending a response.
- CICS regionOne running copy of CICS, with its own programs, files and users. A site typically runs several.
- Transaction IDA four-character code that tells CICS which program to run, typed on the screen or triggered by a key.
- BMS mapThe definition of a CICS screen: where each field sits, how long it is, and how it is highlighted.
- Pseudo-conversationalThe CICS programming style where a program ends after sending each screen, rather than waiting for the user to reply.
- Online transaction processingHandling many small pieces of work in real time while someone waits: a card payment, a balance check, a seat booking.