CICS is one of the most successful software products in the history of computing. Tens of thousands of installations and millions of end-users exploit the facilities of CICS every day in enterprises ranging from among the largest in the world, with tens of thousands of concurrent users, to very small companies with only a few users.

Various names for this class of software product include

• Transaction Processing Monitor
• On-Line Resource Manager
• Data Communications Middleware
• Terminal Monitor
• ... and others

CICS has been generally available since 1969, and versions for the DOS (now VSE) environment have been available since 1970 or so. CICS, the Customer Information Control System was jointly been developed by IBM and ..., the electric utility serving the Chicago, Illinois area. Its original purpose was to provide an on-line interface to the utility's customer information -- names, addresses, meter readings, payments and balances, service orders, and the like.

In the mid-1980s, IBM established a performance benchmarking center in Dallas, and the Swami was the first technical staff member in that organization. In his performance and benchmarking experience, most of the performance benefit possible from optimum tuning of batch and on-line workloads comes from simple tuning of VSAM data sets and the program access specifications (JCL, CICS FCT options, etc.) for them.

If you wanted to know how to do this, you've found the right place!

CICS

The Customer Information Control System, a collection of management programs, interfaces, commands, and tables along with the programming subsystems that implement them, for managing server resources to optimally process many diverse transactions retrieving and updating many diverse files and databases concurrently, with speed, accuracy, and reliability.

System Services

CICS provides system management services to manage multi-tasking, file processing, storage management, terminal communications and a host of ancillary services, such as queue management, journal control, and error recovery services.

Application Programming Interfaces

CICS provides APIs for COBOL, PL/I, C, S/390 Assembler and some other programming languages on other than System/390 or zSeries processors.

File Management

CICS File Services support access to basic operating system file subsystems, such as VSAM, and database subsystems such as DL/I and DB2 in System/390 environments. In other environments, file and databases supported by those environments are frequently supported by CICS. CICS File Management will automatically journal and log file information for recovery if requested.

Task Management

CICS Task Management supports the concurrent processing of multiple user transactions, overlapping processing of one transaction's processing with periods when other transactions are waiting for external events, such as file input/output operations. These tasks can be prioritized by a scheme providing for operator, terminal, and transaction priority specifications to ensure that critical tasks recieve access to the system resources required to meet the organization's business objectives.

Storage Management

CICS provides storage management services to efficiently allocate system main storage as needed by the tasks active within the system.

Terminal Management

Terminal Management provides support for input and output mapping of datastreams from and to user terminals and other network devices to and from the system and user transaction processing programs.