Device Address Specifications, Assgn SYS010,FEF

Understanding tool provides a graphical analysis of your VSE/ESA JCL job stream. You can find further details at the following World Wide Web sites:

http://www.software.ibm.com/ad/va2000

http://www.software.ibm.com/ad/cobol

The JCL Analyzer is shipped as part of VSE Central Functions in VSE/ICCF library 59. It consists of a number of members, including ARDWREAD, which is a detailed description of the JCL Analyzer and its functions. All the other related library member names begin with the characters ARDW.

There is a brief description of this new function in the manual, VSE/ESA

Enhancements Version 2 Release 3, SC33-6629

4.3.6 Device Address Specifications

In VSE, the Logical Unit Address, is the symbolic link between the program and the external units (tape drive, printer, and so on) it uses. The Logical Unit Address is a name in the form of SYSnnn, such as SYS004 or SYSLST. The Logical Unit Address is specified by the programmer on the DTF using the DEVADDR=SYSnnn keyword; for this reason, it is often referred to as the

²Device Address², a term easily confused with ²Unit Address², which refers to the external unit associated with the Logical Unit Address, such as the 3205 printer at address 00E.

In other words, the terms Logical Unit Address and Device Address both refer to the SYSnnn name, where Unit Address refers to the hardware device at address CUU.

In the VSE JCL, the ASSGN statement is used to associate a Device Address to a Unit Address; for example:

// ASSGN SYS010,FEF

where SYS010 is the device address specified in the program, and FEF is the unit address of a real or virtual printer device.

An ASSGN statement is normally required for every non-disk file used by the program, although Tape Management Software products generally remove the requirement for tapes.

There is no exact equivalent for the Device Address in MVS JCL. The association between a file and a particular device is established by Device Allocation, a system function invoked by the initiator. The equivalent of the above ASSGN card depends on what DDNAME is used in MVS for a particular file, which could be, for example:

//SYS010 DD SYSOUT=...

//REPORT1 DD SYSOUT=...

One may wonder, when converting VSE JCL to MVS, what to do with the Device Addresses, ASSGN cards, and what DDname should be used for card and print files. Here are some guidelines:

∙For disk - the DEVADDR should be ignored, and the DTFname should be used as MVS DDname.

∙For labeled tape - the DEVADDR should be ignored, except when the ASSGN statement specifies a tape density, or when assigning several files to the same unit. The DTFname should be used as MVS DDname.

80VSE 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 Device Address Specifications, Assgn SYS010,FEF, SYS010 DD SYSOUT=, REPORT1 DD SYSOUT=

Models: OS/390