Harold Grovesteen wrote:
I worked on DOS/VS systems back in the mid- to late 1970's.
While DOS/VS has some extent protections as mentioned,
actual management of space on volumes is manually performed.
This was usually managed by the system programmer's. The
sysprog (usually only one) had to know what was where.
I would to add to that, that due to this need for manually maintaining the location of all datasets (files) on the system, many shops wrote their own (or used someone else's) LVTOC ("List VTOC") utility, that would not only produce a report of all of the files and their locations on each disk volume (in both CCHH format as well as in TTTT relative track format as well), but would also identify all "gaps" or free spaces as well, making it much easier to manually "locate" space for new files.
Typically, there were large free spaces on one or more volumes where temporary work files could be allocated (with a zero days expiration date), whereas most permanent files (that never expired) would have their DLBL and EXTENT information added to the system's "STDLABEL" or "PARSTD" startup procedures (PROCs).
That way, when you submitted your job to run the program designed to update your file, your JCL wouldn't need to have any DLBLs or EXTENTs in it (because they were already defined in the system's label area). This made it much less likely to make mistakes.
You can think of the system STDLABEL and PARSTD labels as a type of "catalog". If you wanted to "catalog" a file, you added it to the appropriate label area. If you wanted to delete it, you would removed it.
But as mentioned in my and Harold's posts, it was all MANUAL. The system standard labels (STDLABEL) and partition standard labels (PARSTD) were all MANUALLY maintained, and only updated when needed (which was rarely).
Welcome to the primitive world of DOS/VS! :)
--
"Fish" (David B. Trout)
Software Development Laboratories
mail: fish@...
