<database> (VSAM) An IBM disk file storage scheme first used
in S/370 and virtual storage. VSAM comprises three access
methods: Keyed Sequenced Data Set (KSDS), Relative Record
Data Set (RRDS), and Entry Sequenced Data Set (ESDS).
Both IMS/DB and DB2 are implemented on top of VSAM and use
its underlying data structures.
<operating system> (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.
