[TriLUG] MVS mainframes
dave at jamsoft.com
Thu Jun 11 14:13:08 EDT 2009
In the late 80s I spent a couple years in a large COBOL shop in the insurance industry, finished up school, then joined Amdahl on the hardware side of things. Both involved MVS though in much different capacities.
First off, unless a user is part of the operations or systems programming staff, they're typically not doing much, if anything, with the MVS console or JCL/REXX. What they do have are app(s) served up typically via a "3270" terminal (named after the IBM hardware model) - software emulators these days and the user is presented with a custom app menu/login screen. Even now you'll see office workers or clerks with a pared-down Linux or Windows box sitting in front of them, often with a window open that looks curiously like an old green CRT. That's the 3270 emulator, talking to a corporate mainframe either with a hardwired connection on the PC or telnet through IP.
Application programmers work within an editor (I used ROSCOE) and from within the editor submit compile and run jobs into a queue for batch apps, or compile and deploy interactive apps into a framework like CICS. Today's deploying an app into a web framework like JBoss or Glassfish reminds me very much of that. In general there's a lot of stuff happening today that was invented and implemented decades ago on mainframes, just now re-emerging in a lower cost, more user-centric environment. For instance, MVS could be IPLed (booted) on bare metal, or run atop a hypervisor called VM, aside other instances of MVS or other mainframe OSes. Sound familiar?
There's a whole lot I've forgotten, of course, but the feel of the mainframe environment is much more locked down, structured, and application centric. Using UNIX was very liberating to me. The terminology is very different from UNIX/Linux too, although a lot of the pieces are functionally the same.
----- "Andrew Gray" <andrew.james.gray at nc.rr.com> wrote:
> Does anyone have experience with MVS mainframes who might be able to
> shed some light on how they work from a users point of view? I am
> looking for work and was contacted about a position that entails
> with one of these mainframes. I have looked at the wikipedia entry
> am unsure how much different it would be from using unix or linux. I
> took a year of Red Hat in college and had played with FreeBSD and a
> couple distros for some time before that. So basically I am more than
> comfortable with linux and run it full time and am wondering how
> difficult it would be to pick up and how different it would be.
> -Thanks for any help
> Andrew Gray
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