What is Data Spaces mapping for VSAM files?

[pinball]

Hi,

What is Data Spaces mapping for VSAM files? We have heard about this from an expert at my shop who refused to give any further pointers on it. Any direction will be great on this! Thanks for your help.

[enrico-sorichetti]

We have heard about this from an expert at my shop who refused to give any further pointers on it.

not much of an expert IMNSHO

Vsam data space belong to the early times of Vsam mvs architecture

OUT ( once upon a time )
the catalogs where NOT icl catalogs and all the sam allocations ( rough approach ) were done using a sub allocation technique
out of a data space ...
so the steps to define a CLUSTER were
define a dataspace on a volume
define a cluster inside the data space

at that time using vsam vas a bit more complicated than it is nowadays

for example, there was something called the ownership bit and a volume was owned by a single catalog
so for a complex/large environment the allocation planning was a bit more complicated
define how many catalogs to use assign to a catalog a set of volumes and so on...