LPAR

Logically PARtitioned mode

LRECL

Logical RECord Length

LRU

Least Recently Used, Line

 

Replaceable Unit

LSPR

Large Systems Performance

 

Reference

LSR

Local Shared Resources

LTM

Local Transport Mechanism

LU

Logical Unit

LUP

Logical User Profile

MAPS

SNA Network Interconnecting

 

Package

MAS

Multi-Access Spool

MB

MegaByte

MCS

Multiple Console Support

MCSOPER

MVS Console Support

 

OPERator

MCT

Master Control Table

MGCR

Master Get Command

 

Routine

MIH

Missing Interruption Handler

MPF

Message Processing Facility

MQI

Message Queue Interface

MQSERIES

Messaging and Queuing

 

SERIES

MRO

Multi-Region Operation

MS

Migration System

MSHP

Maintain System History

 

Program

MVS

Multiple Virtual Storage

MVS/BDT

Multiple Virtual Storage/Bulk

 

Data Transfer

MVS/DFP

Multiple Virtual Storage/Bulk

 

Data Transfer

MVS/ESA

Multiple Virtual

 

Storage/Enterprise Systems

 

Architecture

MVS/RSU

MVS Recommended Service

 

Upgrade

NCP

Network Control Program

NDF

Network Definition Facility

NFS

Network File System

NJE

Network Job Entry

NSR

Network Service Request

OC

Operator Communication

OCCF

Operator Communications

 

Control Facility

OCO

Object Code Only

OE

Order Entry

OEM

Original Equipment

 

Manufacturer

OGL

Overlay Generation Language

OLPD

On-Line Problem

 

Determination

ONC

Open Network Computing

OPC

Operations, Planning &

 

Control

OPR

OPeRations

OPTCD

OPtional Control Program

 

Service

OS

Operating System

OS/2

Operating System/2

OS/390

Operating System/390

OS/VS

Operating System/Virtual

 

Storage

OSA

Multi-Access Spool

OSA

Open Systems Adapter

OSF

Operational Support Facility

OUTLIM

OUTput LIMiting facility

PARMLIB

PARaMeter LIBrary

PC

Personal Computer

PCB

Program Control Block

PCCU

Primary Communication

 

Control Unit

PCLK

Personal Computer Link

 

Feature

PCT

Program Control Table

PDB

Page Description Block

PDF

Process Control Block

PDS

Partitioned Data Set

PEND

POWER END

PER

Program Event Recording

PERT

Program Evaluation and

 

Review Techniques

PIOCS

Physical Input Output Control

 

System

PKZIP

A data Compression Program

PL/1

Programming Language 1

PL/I

Programming Language 1

PLT

Program List Table

POWER

Priority Output Writers,

 

Execution processor, and

 

input Readers

List of Abbreviations 587

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IBM OS/390 manual Series, Power END
Page 610 Page 612

OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.
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