V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

DOS360
       Disk ??? Operating System / 360 (OS, IBM S/360), "DOS/360"


The Free On-line Dictionary of Computing (30 December 2018):

DOS/360

    The operating system announced by IBM
   at the low end for the System/360 in 1964 and delivered in
   1965 or 1966.

   Following the failure of OS, IBM designed DOS for the low
   end machines, able to run in 16KB(?) and 64KB memory.

   DOS/360 used three memory partitions, but it had no serious
   memory protection.  The three partitions were not
   specialised, but frequently one was used for spooling
   punched cards to disk, another one for batch job
   execution and another for spooling disk to printers.

   With DOS/VS, introduced in 1970, the number of partitions was
   increased, virtual memory was introduced and the minimum
   memory requirements increased.

   Later they released DOS/VSE and ESA/VSE.  DOS/360 successors
   are still alive today (1997) though not as popular as in the
   late 1960s.

   Contrary to the Hacker's Jargon File, GECOS was not copied
   from DOS/360.

   (1997-09-22)