I meant "virtual machine" as a metaphor, not in a technical sense. Arguably not a great one, as it's much more integrated into its host than any actual virtual machine is.
My point is that MVS runs the hardware, and USS depends on MVS. sas On Mon, Apr 13, 2020 at 1:15 PM Kirk Wolf <[email protected]> wrote: > z/OS UNIX is nothing like a virtual machine running under z/OS. > It is a bunch of services (APIs) and programs that practically any z/OS job > or address space can use. > > Like John mentioned, your COBOL program running in a JES2 address space can > decide long after it starts to make a syscall by calling a BPXxxxxx > service. The COBOL/JES2 initiator address space will be "blind dubbed" to > become a z/OS UNIX process. Is the COBOL program now running "under" z/OS > UNIX? is it running in a "VM"? I don't believe that those are accurate > characterizations. ISTM that many people perceive z/OS UNIX like the > old OS/2 DOS "penalty box", but that is not a good comparison either. > > > > On Mon, Apr 13, 2020 at 11:14 AM Steve Smith <[email protected]> wrote: > > > I'll dispute that. MVS manages hardware, dispatching, memory, DASD* and > > I/O. USS "rides" on the back of those. I grant that USS is Unix (and > > Posix), but it's practically a virtual machine on top of MVS. Contrast > > with z/Linux. > > > > sas > > *... i.e. it's closer to the hardware anyway. USS filesystems use MVS > > datasets for containers. > > > > On Mon, Apr 13, 2020 at 11:17 AM Charles Mills <[email protected]> wrote: > > > > > Actually, I considered asserting that there is no such thing as running > > on > > > z/OS NOT under UNIX. <g> > > > > > > I believe that "z/OS is UNIX" is a true statement. > > > > > > Most of us in this group think of z/OS as a bunch of traditional stuff > > > with USS glued on top. From the Open Group's legal point of view, z/OS > is > > > UNIX with some extra, proprietary stuff thrown in (as is Windows > Server). > > > > > > USS is not something you "run under." USS is a set of interfaces into > > > various z/OS services. As is JCL. As is LE. As is TSO. > > > > > > Charles > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
