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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
 | This article's style of writing may not reflect the encyclopedic tone used on Wikipedia. (March 2021) |
| z/OS | |
|---|---|
 | |
| Developer | IBM |
| Written in | primarily PL/X, HLASM, and C/C++[1] |
| OS family | |
| Working state | Current |
| Source model | Closed source with open source components |
| Initial release | March 30, 2001 (V1R1, announced October, 2000) |
| Latest release | Version 3.2 (V3R2) / September 30, 2025 |
| Marketing target | Enterprise / Mainframes |
| Available in | English and other languages |
| Package manager | SMP/E |
| Supported platforms | z/Architecture |
| Kernel type | Monolithic (uniquely hardware-assisted) |
| Userland | MVS, UNIX System Services |
| Default user interface | ISPF, z/OS Management Facility |
| License | Proprietary monthly license charge (MLC); pricing available based on actual use (VWLC, EWLC, AWLC, EAWLC, IWP); reduced pricing options (zELC, zNALC, "Solution Edition") for many applications |
| Official website | ibm |
| History of IBM mainframe operating systems |
|---|
z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000.[2] It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions.[NB 1] Like OS/390, z/OS combines a number of formerly separate, related products, some of which are still optional. z/OS has the attributes of modern operating systems but also retains much of the older functionality that originated in the 1960s and is still in regular use—z/OS is designed for backward compatibility.
z/OS supports[NB 2] stable mainframe facilities such as CICS, COBOL, IMS, PL/I, IBM Db2, RACF, SNA, IBM MQ, record-oriented data access methods, REXX, CLIST, SMP/E, JCL, TSO/E, and ISPF, among others.
z/OS also ships with a 64-bit Java runtime, C/C++ compiler based on the LLVM open-source Clang infrastructure,[3] and UNIX (Single UNIX Specification) APIs and applications through UNIX System Services – The Open Group certifies z/OS as a compliant UNIX operating system – with UNIX/Linux-style HFS[NB 3][NB 4] and zFS[NB 5] file systems. These compatibilities make z/OS capable of running a range of commercial and open-source software.[4] z/OS can communicate directly via TCP/IP, including IPv6,[5] and includes standard HTTP servers (one from Lotus, the other Apache-derived) along with other common services such as SSH, FTP, NFS, and CIFS/SMB. z/OS is designed for high quality of service (QoS), even within a single operating system instance, and has built-in Parallel Sysplex clustering capability.
z/OS has a Workload Manager (WLM) and dispatcher which automatically manages numerous concurrently hosted units of work running in separate key-protected address spaces according to dynamically adjustable goals. This capability inherently supports multi-tenancy within a single operating system image. However, modern IBM mainframes also offer two additional levels of virtualization: LPARs and (optionally) z/VM.
From its inception z/OS has had tri-modal addressing (24-bit, 31-bit, and 64-bit). Up through Version 1.5, z/OS itself could start in either 31-bit ESA/390 or 64-bit z/Architecture mode, so it could function on older hardware, albeit without the ability to run 64-bit applications on those machines. (Only the newer z/Architecture hardware manufactured starting in the year 2000 can run 64-bit code.) IBM support for z/OS 1.5 ended on March 31, 2007, and since then, z/OS is supported only on z/Architecture mainframes and runs exclusively in 64-bit mode. Application programmers can still use any addressing mode: all applications, regardless of their addressing mode(s), can coexist without modification, and IBM maintains a commitment to tri-modal backward compatibility. However, increasing numbers of middleware products and applications, such as DB2 Version 8 and above, now require and exploit 64-bit addressing.
IBM markets z/OS as its flagship operating system,[6] suited for continuous, high-volume operation with high security and stability.
z/OS is available under standard license pricing and via IBM Z New Application License Charges (zNALC) and "IBM Z Solution Edition", two lower-priced offerings aimed at supporting newer applications ("new workloads").[7] U.S. standard commercial z/OS pricing starts at about US$125 per month, including support, for the smallest zNALC installation running the base z/OS product plus a typical set of optional z/OS features.
z/OS introduced Variable Workload License Charges (VWLC)[8] and Entry Workload License Charges (EWLC)[9] which are sub-capacity billing options. VWLC and EWLC customers only pay for peak monthly z/OS usage, not for full machine capacity as with the previous OS/390 operating system. VWLC and EWLC are also available for most IBM software products running on z/OS, and their peaks are separately calculated but can never exceed the z/OS peak. To be eligible for sub-capacity licensing, a z/OS customer must be running in 64-bit mode (which requires z/Architecture hardware), must have eliminated OS/390 from the system, and must e-mail IBM monthly sub-capacity reports. Sub-capacity billing substantially reduces software charges for most IBM mainframe customers.[10] Advanced Workload License Charges (AWLC) is the successor to VWLC on mainframe models starting with the zEnterprise 196, and EAWLC is an option on zEnterprise 114 models. AWLC and EAWLC offer further sub-capacity discounts.
z/OS supports 64-bit addresses for both virtual[11] and real addresses. Within each address space, z/OS initially permitted the placement of only data, not code, above the 2 GiB bar. z/OS enforced this distinction primarily for compatibility reasons. There are no architectural impediments to allowing more than 2 GiB of application code per address space; Linux on IBM Z supports it, for example. IBM has started to allow Java code running on z/OS to execute above the 2 GiB bar, for performance reasons.
Starting with z/OS Version 2 Release 3, code may be placed and executed above the 2 GiB bar. However, very few z/OS services may be invoked from above the bar.
Memory above the bar is obtained as "Large Memory Objects" in multiples of 1 MiB (with the expectation that applications and middleware will manage memory allocation within these large pieces). There are three types of large memory objects:
z/OS Encryption Readiness Technology (zERT) monitors, records, and reports details of z/OS cryptographic network protection. It is a feature of z/OS V2R3 (and later releases) Communications Server component.[12]
With zERT, the TCP/IP stack acts as a focal point in collecting and reporting the cryptographic security attributes of IPv4 and IPv6 application traffic that is protected using the TLS/SSL, SSH and IPSec cryptographic network security protocols. The collected connection level data is written to SMF in new SMF 119 subtype 11 records for analysis.[13]
In certain environments, the volume of SMF 119 subtype 11 records can be large. The zERT aggregation function provides an alternative SMF view of the collected security session data. This alternate view is written in the form of new SMF 119 subtype 12 records that summarize the use of security sessions by many application connections over time and which are written at the end of each SMF interval. This alternate view condenses the volume of SMF record data while still providing all the critical security information.
z/OS Management Facility (z/OSMF) is enhanced to provide a plug-in named IBM zERT Network Analyzer. IBM zERT Network Analyzer is a web-based graphical user interface that z/OS network security administrators can use to analyze and report on data reported in zERT Summary records. With the zERT Network Analyzer, a z/OS network security administrator (typically a systems programmer with responsibility over z/OS Communications Server) can import SMF zERT summary records into a Db2 for z/OS database and then build and run custom queries against that data.
Operational data is data that z/OS system produces when it runs. This data indicates the health of the system and can be used to identify sources of performance and availability issues in the system. IBM Z Operational Log and Data Analytics and IBM Z Anomaly Analytics with Watson collect IT operational data from z/OS systems, analyze and provide insights about the operational data.
IBM Z Operational Log and Data Analytics collects IT operational data from z/OS systems, transforms it to a consumable format, and streams it to third-party enterprise analytics platforms like the Elastic Stack and Splunk, or to the included operational data analysis platform. The included insights can help to visualize and search operational data to help identify the cause of operational issues.[14]
IBM Z Anomaly Analytics with Watson collects IT operational data from z/OS systems, uses historical IBM Z metric and log data to build a model of normal operational behavior, then analyzes real-time operational data through comparison with the model of normal operations to detect anomalous behavior, and notifies IT operations of the anomalous behavior to identify incidents that might lead to business disruption.[15]
IBM Z Operational Log and Data Analytics collects and analyzes both structured and unstructured data, including the following types of operational data:[16]
IBM Z Anomaly Analytics with Watson collects data from multiple IBM Z systems and subsystems, including IBM Db2 for z/OS, IBM CICS Transaction Server for z/OS and IBM MQ for z/OS.[17] The following types of operational data are collected:
| Order No. | Announced | Shipped | Support dropped |
Rel # | Version |
|---|---|---|---|---|---|
| 5694-A01 | 2000-10-03 200-352 |
2001-03-30 | 2004-03-31 | 1 | 1 |
| 5694-A01 | 2001-09-11 201-248 |
2001-10-26 | 2004-10-31 | 2 | |
| 5694-A01 | 2002-02-19 202-031 |
2002-03-29 | 2005-03-31 | 3 | |
| 5694-A01 | 2002-08-13 202-190 |
2002-09-27 | 2007-03-31 | 4 | |
| 5694-A01 | 2004-02-10 204-017 |
2004-03-26 | 2007-03-31 | 5 | |
| 5694-A01 | 2004-08-10 204-180 |
2004-09-24 | 2007-09-30 | 6 | |
| 5694-A01 | 2005-07-27 205-167 |
2005-09-30 | 2008-09-30 | 7 | |
| 5694-A01 | 2006-08-08 206-190 |
2006-09-29 | 2009-09-30 | 8 | |
| 5694-A01 | 2007-08-08 207-175 |
2007-09-28 | 2010-09-30 | 9 | |
| 5694-A01 | 2008-08-05 208-186 |
2008-09-26 | 2011-09 | 10 | |
| 5694-A01 | 2009-08-18 209-242 |
2009-09-25 | 2013-09 | 11 | |
| 5694-A01 | 2010-07-22 210-235 |
2010-09-24 | 2015-09 | 12 | |
| 5694-A01 | 2011-07-12 211-252 |
2011-09-30 | 2017-09 | 13 | |
| 5650-ZOS | 2013-07-23 213-292 |
2013-09-30 | 2019-09 | 1 | 2 |
| 5650-ZOS | 2015-07-28 215-267 |
2015-09-30 | 2021-09 | 2 | |
| 5650-ZOS | 2017-07-17 217-246 |
2017-09-27 | 2022-09-30 | 3 | |
| 5650-ZOS | 2019-02-26 219-013 |
2019-09-30 | 2024-09-30 | 4 | |
| 5650-ZOS | 2021-06-27 221-260 |
2021-09-30 | 2026-09-30[18] | 5 | |
| 5655-ZOS | 2023-02-28 223-012 |
2023-09-29 | TBA | 1 | 3 |
| 5655-ZOS | 2025-07-22 AD25-0005 |
2025-09-30 | TBA | 2 | |
Legend: Supported Latest version | |||||
| Supercomputer | |
|---|---|
| Server, mainframe | |
| Desktop, workstation | |
| Point of sale | |
| Projects | |
| Related | |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
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. Like OS/390, z/OS combines a number of formerly separate, related products, some of which are still optional. z/OS has the attributes of modern operating systems but also retains much of the older functionality that originated in the 1960s and is still in regular use—z/OS is designed for backward compatibility.
International Business Machines Corporation, doing business as IBM (nicknamed Big Blue), is an American multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is a publicly traded company and one of the 30 companies in the Dow Jones Industrial Average. IBM is the largest industrial research organization in the world, with 19 research facilities across a dozen countries; for 29 consecutive years, from 1993 to 2021, it held the record for most annual U.S. patents generated by a business. IBM was founded in 1911 as the Computing-Tabulating-Recording Company (CTR), a holding company of manufacturers of record-keeping and measuring systems. It was renamed "International Business Machines" in 1924 and soon became the leading manufacturer of punch-card tabulating systems. During the 1960s and 1970s, the IBM mainframe, exemplified by the System/360 and its successors, was the world's dominant computing platform, with the company producing 80 percent of computers in the U.S. and 70 percent of computers worldwide. Embracing both business and scientific computing, System/360 was the first family of computers designed to cover a complete range of applications from small to large. IBM entered the microcomputer market in 1981 with the IBM Personal Computer; its architecture remains the basis for the majority of personal computers sold today. The company later also found success in the laptop space with the ThinkPad. Since the 1990s, IBM has concentrated on computer services, software, supercomputers, and scientific research; it sold its microcomputer division to Lenovo in 2005. IBM continues to develop mainframes, and its supercomputers have consistently ranked among the most powerful in the world in the 21st century. As one of the world's oldest and largest technology companies, IBM has been responsible for several technological innovations, including the Automated Teller Machine (ATM), Dynamic Random-Access Memory (DRAM), the floppy disk, Generalized Markup Language, the hard disk drive, the magnetic stripe card, the relational database, the SQL programming language, and the Universal Product Code (UPC) barcode. The company has made inroads in advanced computer chips, quantum computing, artificial intelligence, and data infrastructure. IBM employees and alumni have won various recognitions for their scientific research and inventions, including six Nobel Prizes and six Turing Awards.
IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the computer market with the 7000 series and the later System/360, followed by the System/370. Current mainframe computers in IBM's line of business computers are developments of the basic design of the System/360.
Linux on IBM Z, Linux on zSystems, or zLinux are collective terms for the Linux operating system compiled to run on IBM mainframes, especially IBM Z, zSystems, and LinuxONE servers. Similar terms which imply the same meaning are Linux/390, Linux/390x, etc. The three Linux distributions certified for usage on the IBM Z hardware platform are Red Hat Enterprise Linux, SUSE Linux Enterprise Server, and Ubuntu.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Brown v. Board of Education in 1954.
