System Generation (OS)
System Generation (SysGen) is a two-stage process for installing or updating OS/360 and systems derived from it. There are similar processes for, e.g., DOS/360, which this article does not cover.
The SysGen process runs as a series of jobs under the control of the operating system. For new installations, IBM provides a driver system, which is not intended for production use.
Stage 1 is the compilation of a sequence of macroinstructions describing the configuration to be installed or updated. The assembler does not actually compile any object code, but instead compiles a series of PUNCH pseudoinstructions in order to generate a job stream for Stage 2. The Sysgen can be any of several types:
- Full generation of the operating system.
- Generation of compilers and associated libraries.
- Updating of the I/O configuration
The Stage 2 jobstream uses a variety of utilities, including the assembler and linkage editor.
This process is now obsolete; it was initially replaced by the use of SMP/E, IOCP and MVSCP, then later by HCD[1].
References
- ^ z/OS Hardware Configuration Definition Planning, Document Number GA22-7525-13