Command CICS
| Company type | Software |
|---|---|
| Industry | Computer software |
| Founder | Ken Dakin |
| Headquarters | Naples , United States |
Area served | Worldwide |
| Products | Middleware for CICS macro to command level transition |
| Owner | Advanced Software Products Group, Inc. |
Command CICS or Command-CICS is a software solution designed to assist organizations in transitioning from "Macro level" CICS to "Command level" CICS without the need for rewriting code. This enables seamless upgrades to newer CICS releases that have discontinued support for macro-level applications. Although newer CICS versions offer substantial benefits, many existing applications were incompatible unless businesses ran two distinct CICS versions concurrently on the same operating system, leading to challenges in operations, maintenance, and licensing.
History
CICS was initially introduced by IBM in the late 1960s, utilizing IBM Assembler macros to produce the API system calls directed at the CICS teleprocessing monitor kernel, regardless of whether the software was developed in COBOL or PL/1. Ken Dakin, CEO of APT Ltd. in the United Kingdom, created middleware to resolve this compatibility challenge. Although IBM did not initially pursue this approach, Dakin’s innovation addressed the expensive necessity for clients to convert or rewrite vast numbers of application programs when adopting new CICS versions.
Macro level emulation
Command-CICS operates by intercepting macro-level applications through a Link-edited (static) "stub" inserted before the Load module (MVS) or Phase (DOS/VSE). When control is passed from the CICS Program Control Program (PCP), it establishes a "pseudo macro level" environment with pointers referencing a simulated "Common System Area" (CSA), Transaction Control Area plus Transaction Work Area (TCA+TWA), and pseudo Terminal Control Terminal Entry (TCTTE), thereby mimicking macro-level structures. Prior to transferring control to the original program entry point, Command-CICS configures general purpose registers R13 and R12 to point to these emulated control blocks.
In a genuine macro-level setup, the CSA contains pointers to CICS kernel components such as File Control Program and Storage Control Program; Command-CICS redirects these pointers within its CSA to its own entry points. This method also supports debugging application program calls using CEDF under Command-CICS.
Macro interface
The application executes standard machine code instructions until it encounters its first macro-level API invocation, incurring no overhead until that moment. Once the API call exits the application, Command-CICS assumes control and substitutes the original linkage with an equivalent Command-level call. Early Command-level CICS implementations employed the "Exec Interface Program" (DFHEIP) to translate Command calls back into macro calls, introducing minimal overhead during CICS interactions. Subsequent CICS versions processed API calls directly, removing backward compatibility overhead entirely.
Marketing
Initially marketed by APT Ltd in the United Kingdom and APT International throughout Europe and worldwide, Command-CICS is now distributed by Advanced Software Products Group, Inc., headquartered in Naples, Florida, United States.
Competition
A comparable product is CICS/COMET for z/OS from UNICOM Systems Inc., which incurs some overhead due to its reliance on dynamically added stubs.
External links
- [1] IBM site for Command/CICS including a link to the UNICOM page
- [2] ASPG site
- Official IBM CICS website