The Evolution of CICS

The Evolution of CICS: CICS - State of the Art (1974)

Preface: With each new version and release of the Customer Information Control System (CICS), the product introduced support of new or improved technologies. When reviewing the evolution of CICS, one has to remember the date of the product enhancement, and then consider the nature of the enhancement and why it was important at the time. This article examines the CICS "State of the Art" relevant in 1974.

1974 was an exciting time for CICS. Only recently had CICS begun to support the new IBM 3270 Information Display Station and now the product entered a new era, providing support for virtual storage systems. CICS/VS 1.0 shipped in June 1974 with enhancements in all functional areas of the product; increased reliability, increased usability, expanded application and system services, new data communications support and new data base support.

The rapid acceptance of CICS by customers to be their choice for online transaction processing was met with a rapid response on the part of CICS Development, responding to popular user requirements as well as adapting to new technologies.

CICS/VS 1.0 was hardly out the door when IBM announced that CICS/VS 1.1 would ship in late 1974 with even greater capability. CICS support of VTAM now included support for intelligent workstations such as the 3600 Finance Communications System, the 3650 Retail Store System and the 3790 Communications System.

For the early users of IMS DL/I with CICS, their patience was rewarded. CICS provided its own support of DL/I's program and data base directories (PDIR and DDIR) which enabled it to now support multiple concurrent CICS applications using DL/I. A far cry from the initial single threaded use of DL/I which was attributed to the nature of IMS Batch DL/I, which was the only form of DL/I available to CICS users.

CICS' previously delivered support for controlled shutdown and warm start, and support for journals and logs with CICS' Journal Control Program, established the base for CICS now to support emergency restart and transaction backout. Early users of CICS (e.g. 1968) had primarily read only applications, but now having experience with online systems, users began to demand the ability to do online updates, and preserve data integrity with dynamic transaction backout or backout as a function of emergency restart. CICS met the challenge and provided that support.

The rapid growth of the CICS product, in terms of its capabilities, and the customer interest in CICS for online transaction processing added still greater impetus for CICS to do more. In late 1974, additional terminal and network support was announced as being included in CICS/VS 1.1. Support for TCAM, which was temporarily dropped from the product, was reinstated. Support for the 3740 and System/7 on binary synchronous lines was provided.

A major enhancement announced for CICS/VS 1.1 was the revision of CICS' support of virtual storage. Adapting to virtual storage environments was not an easy, obvious effort, but in a relatively short period of time, while customers used the initial support of CICS/VS 1.0, CICS Development gained considerable experience and was able to refine its support of storage management. The improved storage management facilities were actually delivered in an interim release of CICS, CICS/VS 1.0.1 in October 1974.