VSE (operating system)

z/VSE (Virtual Storage Extended) is an operating system for IBM mainframe computers, the latest one in the DOS/360 lineage, which originated in 1965. Announced Feb. 1, 2005 by IBM as successor to VSA/ESA 2.7, then-new z/VSE[2][3]was named to reflect the new "System z" branding for IBM's mainframe product line.[4][5]

OS familyDOS/360 and successors
Working stateCurrent
Source modelClosed source
Latest releaseIBM z/VSE V6.2 / December 1, 2017 [1]
Marketing targetIBM mainframe computers
Official websitewww.ibm.com/systems/z/os/zvse/
History of IBM mainframe operating systems

DOS/VSE was introduced in 1979 as a successor to DOS/VS; in turn, DOS/VSE was succeeded by VSE/SP version 1 in 1983, and VSE/SP version 2 in 1985.[6]

It is less common than prominent z/OS and is mostly used on smaller machines.[7][8][9] In the late 1980s, there was a widespread perception among VSE customers that IBM was planning to discontinue VSE and migrate its customers to MVS instead, although IBM relented and agreed to continue to produce new versions of VSE.[10][11]


DOS/360 originally supported 24-bit addressing. As the underlying hardware evolved, VSE/ESA acquired support for 31-bit addressing.[12]

IBM released z/VSE Version 4, which requires 64-bit z/Architecture hardware and supports 64-bit real mode addressing, in 2007. With z/VSE 5.1 (available since 2011)[12] z/VSE introduced 64 bit virtual addressing and memory objects (chunks of virtual storage), that are allocated above 2 GB. The latest shipping release is z/VSE 6.2.0 - available since December 2017,[13] which includes the new CICS Transaction Server for z/VSE 2.2.

User interfaces

Job Control Language (JCL)

A Job Control Language (JCL) that continues in the positional-parameter orientation of earlier DOS systems is z/VSE's batch processing primary user interface.[14][15] There is also another, special interface for system console operators.[16]

Beyond batch

z/VSE, like z/OS systems, had traditionally supported 3270 terminal user interfaces. However, most z/VSE installations have at least begun to add Web browser access to z/VSE applications. z/VSE's TCP/IP is a separately priced option for historic reasons, and is available in two different versions from two vendors. Both vendors provide a full function TCP/IP stack with applications, such as telnet and FTP. One TCP/IP stack provides IPv4 communication only, the other IPv4 and IPv6 communication. In addition to the commercially available TCP/IP stacks for z/VSE, IBM also provides the Linux Fastpath method which uses IUCV socket or Hipersockets connections to communicate with a Linux guest, also running on the mainframe.

Using this method the z/VSE system is able to fully exploit the native Linux TCP/IP stack.[17]

IBM recommends[18] that z/VSE customers run Linux on IBM Z alongside, on the same physical system, to provide another 64-bit application environment that can access and extend z/VSE applications and data via Hipersockets using a wide variety of middleware. CICS, one of the most popular enterprise transaction processing systems, is extremely popular among z/VSE users and now supports recent innovations such as Web services. DB2 is also available and popular.

Device support

z/VSE supports ECKD as well as SCSI devices. Fibre Channel access to SCSI storage devices was initially supported by z/VSE 3.1 on a limited basis (including on IBM's Enterprise Storage Server (ESS), IBM System Storage DS8000, DS6000 series), but the limitations disappeared with 4.2 (thus including IBM Storwize V7000, V5000, V3700 and V9000).[19]

Older z/VSE versions

The last VSE/ESA release - VSE/ESA 2.7 - is no longer supported since February 28, 2007.[20] z/VSE 3.1 was the last release, that was compatible with 31-bit mainframes, as opposed to z/VSE Version 4, 5 and 6. z/VSE 3.1 was supported to 2009.[20] z/VSE Version 4 is no longer supported since October 2014 (end of service for z/VSE 4.3).

For VSE/ESA, DOS/VSE, VSE/SP, see History of IBM mainframe operating systems#DOS/VS

See also


  1. IBM (December 1, 2017). "IBM z/VSE V6.2". IBM. Retrieved March 15, 2018.
  2. "IBM z/VSE V3.1 generally available". February 1, 2005. z/VSE continues the focus on interoperability that began with VSE/ESA Version 2 Release 5, and continued with VSE/ESA Version 2 Release 6 and VSE/ESA Version 2 Release 7
  3. One can find references to "z/VSE V3.0.0" but they refer to Version 3.0.0 of Websphere for z/VSE." "Program Directory for z/VSE" (PDF). IBM WebSphere MQ for z/VSE V3.0.0 is a new member of the WebShere MQ family of messaging products. It is a replacement for MQSeries for VSE/ESA V2.1.2.
  4. Roger Kay (January 13, 2015). "With Z Systems Refresh, IBM Reminds Us That Mainframes Remain Relevant". Forbes. The new system — called IBM z13 and running the fastest ... this latest revision of IBM's time-hallowed product line incorporates new ... fast enough to intervene in time to avert brand damage and lost sales? Well ... What used to be "System z" is now "z Systems," with the current product being the IBM z13.
  5. which in 2015 became "z Systems"
  6. Jim Hoskins; Bob Frank (2003). Exploring IBM Eserver Zseries and S/390 Servers: See Why IBM's Redesigned Mainframe Server Family Has Become More Popular Than Ever. Maximum Press. p. 275. ISBN 978-1-885068-91-0.
  7. Axel Buecker; Boudhayan Chakrabarty; Lennie Dymoke-Bradshaw (2016). "Reduce Risk and Improve Security on IBM Mainframes (Volume 1)". ISBN 0738440108. Extended (z/VSE) is popular with users of smaller mainframe computers.
  8. "Ahead of the Pack". IBM Systems Magazine. At the risk of oversimplification, z/VSE is similar to z/OS but relatively smaller, simpler ... cost-effective
  9. Stedman, Craig (29 Jan 1996). "IBM teaches VM, VSE new mainframe tricks". Computerworld. 30 (5): 39.
  10. Cortese, Amy (21 Aug 1989). "Militant VSE users upbeat but impatient". Computerworld. 23 (34): 17.
  11. Ambrosio, Johanna (23 Jul 1990). "VSE gets jumpstart with sequel". Computerworld. 24 (30): 6.
  12. Ingolf Salm (May 7, 2012). "Virtual Addressing With z/VSE: From 24-Bit to 64-Bit". EnterpriseSystemsMedia.com.
  13. "IBM z/VSE V6.2". IBM z/VSE V6.2 is capable as of December 1, 2017 ...
  14. "Introduction to the New Mainframe: IBM z/VSE Basics" (PDF). March 1, 2016.
  15. "Storage Considerations For the Batch External Interface".
  16. "Hints and Tips for z/VSE 5.2" (PDF).
  17. "The z/VSE Fast Path to Linux on System z".
  18. "z/VSE Fast Path to Linux on IBM Z" (PDF). Both z/VSE and Linux on IBM Z run as z/VM Guests in the same z/VM-mode LPAR .... The use of a z/VM-mode LPAR is recommended.
  19. "z/VSE SCSI Support and Migration Options" (PDF).
  20. "z/VSE 6.2" (PDF). Retrieved March 15, 2018.
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