7.2.1 Accessing the System

Since LOGON to TSO/E is dependent on the telecommunications access method used with TSO/E, the System Standards implemented by the Systems Programmer, and the related program products installed, you should reference the TSO/E Primer and your Systems Programmer for information on logging on to TSO/E.

7.2.2 Entering and Manipulating Data

In ICCF, data is entered and stored as a member of an ICCF library. Data is restricted to 80 byte records in an ICCF library. You may enter data into an ICCF library member from Input, Edit, or Full Screen Edit mode. ICCF allows modification of data stored in members of ICCF libraries only. Modifications are made while in Edit or Full Screen Edit modes and physically change the data on the DTSFILE.

In TSO/E, data is entered and stored in sequential data sets, or partitioned data sets (PDS) using the Interactive System Productivity Facility/Program Development Facility (ISPF/PDF) editor or the TSO/E EDIT command and its subcommands. Most users use ISPF/PDF, rather than the older TSO/E EDIT command, to gain increased usability and improve their productivity. Record formats may be either fixed or variable with a logical record size less than or equal to 255 and a block size less than or equal to track length. A PDS is a data set partitioned into one or more independent groups called members. Each member must have a unique name and can be referred to separately by appending the member name, enclosed in parentheses, to the data set name.

The name you give a data set should follow the TSO/E naming conventions. A TSO/E data set name normally has three fields.

Identification Qualifier - This is always the leftmost qualifier of the full data set name. For TSO/E, this qualifier is the prefix selected in the PROFILE command. If no prefix has been selected, your user ID will be used.

User-Supplied Name - You choose a name for the data sets that you want to identify. It can be a simple name or several simple names separated by periods.

Descriptive Qualifier - The descriptive qualifier is always the rightmost qualifier of the full data set name. It is one of a set of keywords that describe the contents of the data set to the system (that is, ′data′ identifies the data set as uppercase text). A list of standard descriptive qualifiers and the respective contents follows.

Descriptive Qualifier

Data Set Contents

 

 

A S M

Assembler input

 

 

CLIST

TSO/E commands and subcommands

 

 

CNTL

JCL and SYSIN for SUBMIT command

 

 

COBOL

COBOL statements

 

 

DATA

Uppercase text

 

 

FORT

FORTRAN statements

 

 

LINKLIST

Output listing from linkage editor

 

 

LIST

Listings

 

 

LOAD

Load module

 

 

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IBM OS/390 manual Accessing the System, Entering and Manipulating Data, Descriptive Qualifier Data Set Contents
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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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