On Thu, 23 May 2024 22:24:06 -0500, Mike Schwab wrote: > >VSAM came from the Future Systems development as a complete >replacement, Lynn Wheeler has posts about that. >It was cut back to be an addition to MVS, then combined with CVOL >catalogs to ICF. > "complete replacement" of what, specifically? I have heard the assertion that VSAM was intended to replace all other access methods: QSAM, BSAM, BPAM, ...
I have known an OS partisan to rant hereabouts: The MVS catalog tells the OS exactly where a data set resides, whereas with UNIX the programmer must supply such information to access any file. I believe he was referring to pathnames. I have never felt that hardship. UNIX provides alternative facilities: o Mounted filesystems o Symbolic links o Directory hierarchy o The current working directory o Logical filesystems comprising multiple physical volumes, a technique MVS never mastered, partly because of compatibility constraints with BBCCHHR. It was desigh shortsightedness to expose low-level DASD characteristics to high-level programmers. Beyond that, the MVS namespace is woefully small; another archaic and insuperable compatibility constraint. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN