VSEⁿ (''Virtual Storage Extended'') is an

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

for

IBM mainframe IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the large computer market. Current mainframe computers in IBM's line of business computers are developments of the basic design of th ...

computers, the latest one in the DOS/360 lineage, which originated in 1965. 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. In February 2005, IBM announced z/VSE as successor to VSE/ESA 2.7, which was named to reflect the new

System z IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest mod ...

branding for IBM's mainframe product line. In June 2021, 21st Century Software Inc announced that it had licensed the z/VSE source code from IBM with the intention of developing new versions of the operating system. As part of this transfer, z/VSE was renamed to VSEⁿ. It is less common than

z/OS z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions.Starting with the earliest: * O ...

and is mostly used on smaller machines. 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.

Overview

DOS/360 originally used

24-bit Notable 24-bit machines include the CDC 924 – a 24-bit version of the CDC 1604, CDC lower 3000 series, SDS 930 and SDS 940, the ICT 1900 series, the Elliott 4100 series, and the Datacraft minicomputers/ Harris H series. The term SWORD is ...

addressing. As the underlying hardware evolved, VSE/ESA acquired 31-bit addressing capability. IBM released z/VSE Version 4, which requires

64-bit In computer architecture, 64-bit integers, memory addresses, or other data units are those that are 64 bits wide. Also, 64-bit CPUs and ALUs are those that are based on processor registers, address buses, or data buses of that size. A comput ...

z/Architecture z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture, implemented by its mainframe computers. IBM introduced its first z/Architecture- ...

hardware and can use 64-bit real mode addressing, in 2007. With z/VSE 5.1 (available since 2011) z/VSE introduced 64-bit virtual addressing and memory objects (chunks of virtual storage), that are allocated above 2 GB.

User interfaces

Job Control Language (JCL)

Job Control Language Job Control Language (JCL) is a name for scripting languages used on IBM mainframe operating systems to instruct the system on how to run a batch job or start a subsystem. More specifically, the purpose of JCL is to say which programs to run, u ...

(JCL) that continues in the positional-parameter orientation of earlier DOS systems is VSEⁿ's batch processing primary user interface. There is also another, special interface for

system console One meaning of system console, computer console, root console, operator's console, or simply console is the text entry and display device for system administration messages, particularly those from the BIOS or boot loader, the kernel, from the i ...

operators.

Beyond batch

VSEⁿ, like z/OS systems, had traditionally provided

3270 terminal The IBM 3270 is a family of block oriented display and printer computer terminals introduced by IBM in 1971 and normally used to communicate with IBM mainframes. The 3270 was the successor to the IBM 2260 display terminal. Due to the text ...

user interfaces. However, most VSEⁿ installations have at least begun to add

Web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on ...

access to VSEⁿ applications. VSEⁿ's

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

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 The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data ...

. One TCP/IP stack provides IPv4 communication only, the other IPv4 and IPv6 communication. In addition to the commercially available TCP/IP stacks for VSEⁿ, 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 VSEⁿ system is able to fully exploit the native Linux TCP/IP stack. IBM recommends that z/VSE customers run

Linux on IBM Z Linux on IBM Z or Linux on zSystems is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z / IBM zSystems and IBM LinuxONE servers. Similar terms which imply the same meaning are ''Linux/390'', ...

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 Middleware is a type of computer software that provides services to software applications beyond those available from the operating system. It can be described as "software glue". Middleware makes it easier for software developers to implement com ...

CICS IBM CICS (Customer Information Control System) is a family of mixed-language application servers that provide online transaction management and connectivity for applications on IBM mainframe systems under z/OS and z/VSE. CICS family products ...

, one of the most popular enterprise

transaction processing system Transaction processing is a way of computing that divides work into individual, indivisible operations, called transactions. A transaction processing system (TPS) is a software system, or software/ hardware combination, that supports transaction ...

s, is extremely popular among VSEⁿ users and now implements recent innovations such as Web services. Db2 is also available and popular.

Device support

VSEⁿ can use ECKD, FBA and SCSI devices.

Fibre Channel Fibre Channel (FC) is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data. Fibre Channel is primarily used to connect computer data storage to servers in storage area networks (SAN) in commercial data cent ...

access to SCSI storage devices was initially available on z/VSE 3.1 on a limited basis (including on IBM's

Enterprise Storage Server The IBM Enterprise Storage Server (ESS) or the ''Shark'' is an enterprise storage array from IBM. History Originally, in 1998 IBM released the IBM 2105 Versatile Storage Server (VSS). It did not meet commercial success and the successor came in ...

(ESS), IBM System Storage

DS8000 The IBM DS8000 series (early IBM System Storage DS8000 series) is an IBM storage media platform with hybrid flash and hard disk storage for IBM mainframes and other enterprise grade computing environments. Description This series formerly desi ...

, DS6000 series), but the limitations disappeared with 4.2 (thus including

IBM Storwize V7000 IBM Storwize systems were virtualizing RAID computer data storage systems with raw storage capacities up to 32 PB. Storwize is based on the same software as IBM SAN Volume Controller (SVC). Formerly Storwize was an independent data storage organ ...

, V5000, V3700 and V9000).

References

External links

IBM z/VSE website
{{DEFAULTSORT:VSE IBM mainframe operating systems