The Evolution of CICS

The Evolution of CICS: A Product Family is Born (1971)

On June 25, 1971, IBM announced a new version for CICS, with a new name, and also announced two new CICS products, establishing for the first time, a CICS family of products.

The original CICS product (5736-U11) evolved into CICS/OS STANDARD, and two new CICS products were announced for the Disk Operating System (DOS) environment. DOS in the 1970s should not be confused with the software of the same name, introduced with personal computers in the 1980s. DOS of the 1970s later evolved into DOS/VSE (Virtual Storage Extended).

CICS/OS STANDARD Version 2 incorporated the previously distributed CICS Language/Terminal Feature into a single product. By 1971, CICS had already established itself in all industry categories, and a strong request for CICS usability came from the DOS community, which was made up of customers with small and intermediate sized systems.

Don Hilgers was an IBM Systems Engineer, working in northwest Ohio, with accounts such as Ohio Edison, and he was instrumental in adapting CICS to a DOS environment. IBM decided to offer two versions of the DOS-based product, one called CICS/DOS-Entry (DOS/E or DOSE) and another called CICS/DOS-Standard (DOS/S or DOSS).

CICS/DOSE was intended for very small systems with limited storage, and was architected to have only one transaction's data in main storage at one time, "rolling" it out of storage when it was decided to "roll in" another transaction's data to be dispatched next. The "full" CICS/DOSS product was a mirror image of CICS/OS STANDARD, but obviously using DOS-oriented services within CICS rather than OS (MVT, MFT, PCP) services. In many cases, CICS for the DOS environment had to create its own services since the DOS operating system may not have had services comparable to OS.

Terminals supported by the CICS product family grew considerably. CICS support and function was largely driven by marketing objectives, making it attractive to potential customers, either because of the environment supported (OS or DOS) or perhaps the terminals supported. With the 1971 CICS systems, terminal support included such devices as BSC dial terminals, the 2770/2848/2760/1050/2980/7770/S3/S7 and others.

CICS/OS and CICS/DOS introduced support for file browse, enqueue/dequeue on file records, dynamic open/close, time management services, CICS' own storage management (no longer using OS getmain/freemain due to its overhead and lack of an effective subpool mechanism), trace, CICS' own program loader, and more. The CICS evolution was underway.