Record Addressing by KEY

Supply the key as follows:

VSE

READ

filename,KEY

 

 

KEYARG and KEYLEN operands are required in the DTFDA macro.

 

 

 

MVS

READ

decbname, DK,...,keyaddress,blockaddress

 

 

 

Keyaddress points to a field containing the key of the record for which you are searching. Blockaddress points to a field containing sufficient information to identify the track on which the search is to begin.

Reference Methods

The following paragraphs describe record reference by ID and record reference by key. In each method, relative track addressing and actual physical addressing are applicable to VSE and MVS; relative block addressing is applicable only to MVS. The relative block addressing technique locates a block by its position relative to the first block of the data set.

Record Reference by ID

Under VSE, records can be referenced by ID when you specify READID and/or WRITEID in the DTFDA. You must also supply both the track information and the record number in the field specified by SEEKADDR.

Under MVS, records can be referenced by ID when you specify MACRF=(...I...) in the DCB and the type parameter of the READ/WRITE macro contains I (see Figure 42 on page 317).

316VSE to OS/390 Migration Workbook

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IBM OS/390 manual Record Addressing by KEY, Reference Methods, Record Reference by ID

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.