OS/390 Dynamic Allocation and Output Descriptor Macros

Traditional SYSOUT attributes can be specified on the DYNALLOC macro. AFP attributes can be specified on the OUTDES macro.

11.3.4.4 High Level Language Programming Interfaces

COBOL Applications

Creating AFP in COBOL is essentially the same between MVS and VSE. VSE code will run in MVS unchanged. MVS coding will require changes to FDs and File-Control moving to VSE due to the lack of the ability to specify DCB attributes in VSE JCL. See the AFPREBLK program in vsereblk on the Web site for an example of COBOL that runs in both environments. See also above the AFP Toolkit API, which supports COBOL and PL/I.

PL/I

Subject to the same cautions as COBOL, PL/I can also be used for manipulating AFP output.

REXX

In OS/390, REXX does not have the I/O limitations it does in VSE. There are many REXX examples on the Web site.

11.4 Understanding Operational Differences

Similar to the POWER commands in VSE, JES2 commands are used to control PSF printing in OS/390.

11.4.1 Starting and Stopping PSF

There are no PSF/MVS-specific commands. PSF/MVS is automatically started and stopped as a result of JES2 $S PRT and $P PRT commands. Changes to the printer setup attributes and selection criteria are also controlled through the JES2 $TPTR commands.

11.4.2 Command Comparison

Note that VSE/POWER command objects (ªdevnameº) are the names on the PRINTDEV statement in the PSF startup JOB, whereas MVS/JES2 command objects (ªnnnnº) are printer numbers defined to JES2 via the PRT(nnnn) statements.

Table 31 (Page 1 of 2). VSE - OS/390 Command Comparison

VSE or POWER Command

JES2 Command

Comment

 

 

 

 

POWER Command

 

 

 

 

 

 

PSTART devname

$S PRTnnnn

Start the printer

[,classes ]

$T

P R T n n n n , C L = q

- Change SYSOUT Class selected

[, P A R M = . . ]

$T

P R T n n n n , R = d e s t

- Change destinations selected

 

 

 

 

242VSE to OS/390 Migration Workbook

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IBM OS/390 manual Understanding Operational Differences, Starting and Stopping PSF, Command Comparison

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.