The Evolution of CICS

The Evolution of CICS: CICS/VS 1.6 & 31-bit Addressability (1982)

CICS has had a history of staying abreast of new technology. In the early 1980s, the most significant advancement in technology for operating systems environments was the introduction of 31-bit addressing, giving applications and subsystems the ability to address storage above the 16mb line. This new environment was a steep hill for CICS to climb, but the product met the challenge over several releases.

CICS/OS/VS 1.6 was announced on July 22, 1982 (282-130), with a planned availability for December 1982. CICS moved into the 31-bit world with caution, initially announcing only the CICS/OS/VS product to support the new addressing scheme, and then only to a limited degree. A major concern for CICS Development was to introduce the new support without impacting existing applications, and to offer support initially in technical areas that would offer some new advantage to users.

The first CICS support of extended architecture (XA) was to enable temporary storage main storage to reside above the so-called 16mb line. CICS facilities such as the Execution Diagnostic Facility (EDF), dump and trace were enhanced to support 31-bit addressibility as well as previous 24-bit addressing. The CICS GETMAIN command was enhanced to allow applications to request virtual storage above or below the 16mb line. Transactions could be composed of both 24-bit and 31-bit command level programs.

The CICS interface to IMS/VS DB was enhanced to close data bases during emergency restart which could not be successfully backed out. The use of the CICS CEMT RECOVERDB command was enhanced to force end-of-volume for the system log only once to improve data base recovery. The CICS trace facility was enhanced to include response codes from the CICS-IMS interface.

CICS application programming and development was enhanced with the addition of a new browse transaction (CEBR) to display the contents of temporary storage queues. CICS/OS/VS 1.6 allowed both aligned and unaligned maps to be supported. Basic Mapping Support (BMS) maps no longer needed to be in ascending sequence by field position.

The CICS External Security Management (ESM) interface was enhanced for APPLID and terminal validation, as well as DL/I PSB validation. User exit security authorization was improved, the number of security keys was increased from 24 to 64 and a new resource level security value of PUBLIC was introduced.

CICS introduced a new facility called Resource Definition Online (RDO) with initial support for transactions, programs and mapsets. RDO was later further enhanced with online definitions for files, queues and other CICS resources. CICS provided an online RDO transaction called CEDA (CICS execute-level dynamic add) and a batch utility (DFHCSDUP) to add, change, delete, or install resource definitions.

CICS/OS/VS added support for Advanced Program-to-Program Communication (APPC) which involved the use of LU6.2 protocols. APPC offered significant capabilities for CICS systems such that CICS applications could enter into client/server communications, with either of the connected systems acting as the client or the server. The role of a given system could be changed dynamically through programming.