OS/390
| Company type | Operating system |
|---|---|
| Industry | Computer software |
| Founded | 1995 |
| Founder | IBM |
| Defunct | 2004 |
| Successor | z/OS |
| Products | Operating system for IBM System/390 mainframes |
| Owner | IBM |
OS/390 is an IBM operating system created specifically for System/390 IBM mainframe computers.
Overview
Launched in late 1995, OS/390 simplified the packaging and ordering process by combining essential licensed components necessary for a full Multiple Virtual Storage (MVS) operating system. These components comprised:
- Data Facility Storage Management Subsystem Data Facility Product (DFP) – delivers access methods for input/output operations involving devices such as Direct access storage device subsystems, printers, and tape drives, along with utilities and program control features
- Job Entry Subsystem (JES) – facilitates batch job submission and manages printing tasks
- IBM Communications Server – supports communication protocols including Virtual Telecommunications Access Method (VTAM) and TCP/IP
This integrated packaging strategy improved reliability, availability and serviceability (RAS) by minimizing the variety of component combinations that users had to handle. Consequently, it reduced testing and implementation durations while decreasing the frequency of customer-reported problems like Authorized Program Analysis Reports and Program temporary fixes caused by mismatched element versions.
In December 2001, IBM advanced OS/390 with support for 64-bit zSeries processors and introduced new features, renaming it as z/OS. Official support for OS/390 was discontinued by late 2004.