I'm along time out of main frames and things will have moved on my guess is Dumpmaster is software to improve the analysis of the machine dumps one gets when things go wrong on the mainframe, in the 60s and 70s it was just a hex dump but as time past it got more formatted.
I guess you know MVS is the operating system , MVS because its dynamic variable number of partitions as opposed to the old MFT which had a predetermined fixed number, and Job Control Language is the control statement system for running jobs, its very comprehensive but usually a small subset of the parameters are all that's required for testing, we had a specialist team of schedulers for the live stuff.
I guess that's the end of this old guys knowledge
Brian