9.2 ACF/NCP

ACF/NCP in a 37XX controller may itself be completely independent of the operating system in the host, but the generation and loading of such an NCP is very much dependent on the operating system.

9.2.1 Product Installation

Differences in the installation procedures of NCP for VSE and OS/390 are basically the same as those for VTAM. The main steps required to implement an NCP under OS/390 are:

Allocate data sets for use by NCP and the generation process.

The generation process requires three input PDSs and a number of work files in order to process the source statements. The three PDSs, into which the SSP and NCP modules are installed, are:

The data set containing the ACF/SSP modules, which includes the load and dump utilities as well as the NDF generation programs. This is also referred to in the VTAM start procedure (STEPLIB) because VTAM uses it to load the NCP.

The data set containing the ACF/NCP macro statements used to assemble the NCP object modules which are created during the NDF process. It is referred to as SYSLIB in the generation procedure. It is a source library and therefore has DCB=(RECFM=FB,LRECL=80) with a suitable block size.

The data set containing the ACF/NCP modules used in link-editing the NCP into its final home. As a load module library it has DCB=(RECFM=U) .

You must also allocate the data set into which the finished NCP will go (NCPLOAD in our example VTAM start procedure).

Install the SSP and NCP products to the libraries, using SMP/E. Current levels of ACF/NCP and ACF/SSP can be included in the OS/390 SystemPac with the initial installation tasks already completed.

Run the program generation procedure.

9.2.2Program Generation

Generation under VSE and OS/390 is done using NDF. ACF/SSP beginning with Version 3 includes the NCP/EP Definition Facility (NDF), a program used in generating an NCP and/or EP load module. Compared to the old generation processes, NDF can do a program generation four to eight times faster. There is also a time-saving FASTRUN option in NDF which can be used to validate the NCP/EP definition macro coding without invoking the generation process. The control program generation using NDF under VSE is a six step process, while under OS/390 it is a two step process. These steps are submitted as one single job and no operator/programmer intervention is required between the steps. More information on NDF (including samples) can be found in the NCP, SSP, and EP Generation and Loading Guide.

There are differences in the actual coding of the NCP between VSE and OS/390, because the definition statements refer to operating system-dependent facilities. In particular:

192VSE to OS/390 Migration Workbook

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IBM OS/390 manual Acf/Ncp, Program Generation

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.