Points Macro, Relse Macro, Trunc Macro

Notes:

1.VSE: The address is that of a four-byte storage location containing the required record identification in the same form as it is obtained from the NOTE macro.

2.MVS: The blockaddrcss is the address of a fullword on a fullword boundary containing the required record identification in the same form as it is obtained from the NOTE macro.

3.The MVS POINT macro is valid only for BSAM and BPAM.

4.If you specify OPTCD=H in the data control block, the POINT macro instruction can perform record positioning on VSE tapes that contain embedded checkpoint records. Any embedded checkpoint records that are encountered during the record positioning are bypassed and are not counted as blocks spaced over. You must specify OPTCD=H in a JCL DD statement. Do not use the POINT macro instruction to backspace VSE 7-track tapes that are written in data convert mode and which contain embedded checkpoint records.

POINTS Macro

VSE	POINTS	filename
		(1)

MVS	POINT	dcbaddress ,	blockaddress
		(1-12)	(2-12)
			(0)

The POINTS macro in VSE causes tapes to be rewound and positioned to the first record following the label set. To achieve this in MVS, you must specify the hexadecimal value 00000001 in the blockaddress field.

RELSE Macro

VSE	RELSE	filename
		(1)

MVS	RELSE	dcbaddress
		(1-12)

The function of the RELSE macro is the same under VSE and MVS. The MVS RELSE macro is valid only for QSAM and QISAM.

TRUNC Macro

VSE	TRUNC	filename
		(1)

MVS	TRUNC	dcbaddress
		(1-12)

The function of the TRUNC macro is the same under VSE and MVS. The MVS TRUNC macro is valid only for QSAM.

300VSE to OS/390 Migration Workbook

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.

IBM OS/390 manual Points Macro, Relse Macro, Trunc Macro

Models: OS/390