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

VSE
       Virtual Storage Extended (IBM)


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

Virtual Storage Extended
VSE

    (VSE, formerly DOS/VSE) is a
   multitasking, IBM 370-architected operating system
   similar to Multiple Virtual Storage (MVS).

   VSE run jobs in partitions rather than address spaces, and
   uses POWER for input/output rather than JES, but is
   largely similar to MVS.  Subsequent VSE/ESA releases gave
   VSE the XA-370 channel architecture, 31-bit virtual and real
   storage support, and data spaces.  VSE is the IBM operating
   system on one-third of installed IBM 4381s and a significant
   proportion of IBM 9370s as well.  It offers transaction
   processing and batch processing capabilities well beyond
   Virtual Machine's current capabilities, and has a close
   affinity with MVS.

   (1997-06-09)