9.4.2 TCP/IP Configuration

First of all, configure the UNIX System Services (part of the OS/390 base product) in order to enable TCP/IP on OS/390. As a second step you will have to customize TCP/IP on OS/390.

9.4.2.1 TCP/IP Customization

On VSE/ESA, almost all TCP/IP customization information is located in one file, the IPINIT.L initialization file. It contains all the required TCP/IP definitions such as the physical network, links, routing tables, user IDs, and TCP/IP daemons.

On OS/390, the TCP/IP definitions are located in several data sets. This is why you have to customize several data sets in order to migrate your VSE/ESA TCP/IP definitions. Mainly, you have to provide the:

TCPIP.PROFILE (TCP/IP definitions for the physical network, network routing, TCP/IP stack and so on)

TCPIP.DATA (parameters for all TCP/IP server and client functions)

depending on your requirement, some other configuration data sets such as HOSTS.LOCAL (host name to IP address mapping) and other etc files have to be set up.

9.4.2.2 TCP/IP Standard Applications

All TCP/IP for VSE standard applications such as Telnet, FTP or LPR/LPD, are also available with TCP/IP on OS/390. The HTTP server on OS/390 is provided by the Domino Go Web Server or the ICSS (Internet Connection Secure Server). Therefore, migrating to OS/390 doesnt restrict the TCP/IP server and client functionality and can be done with low effort. However, OS/390 users can make use of additional TCP/IP functions such as REXEC, DCE or SMTP.

9.4.3 TCP/IP Related User Data

Dont forget to move your data files that are exclusively used/accessed through TCP/IP. If you have, for example, set up VSE/ESA as a Web server, consider to move the Web server data such as HTML documents, and graphics that are stored in VSE library members or VSAM files. These files should be moved into OS/390 HFS (Hierarchical Filesystem) data sets. Transferring the files could, for example, be done using the FTP function.

9.4.4 TCP/IP Batch Jobs

If you are using batch jobs on VSE to automate TCP/IP client commands such as LPR printing, FTP to automatically transfer files or the Telnet client to access remote TCP/IP systems, take into account that you will have to migrate these batch jobs as well. For the OS/390 system, you have to convert your batch jobs to CLISTs, REXX EXECs or UNIX shell scripts.

9.4.5 User Written TCP/IP Applications

If you have many user written TCP/IP applications on your VSE/ESA system, the migration effort can be considerably high depending on the TCP/IP interface that has been used.

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IBM OS/390 manual 2 TCP/IP Configuration, 3 TCP/IP Related User Data, 4 TCP/IP Batch Jobs, User Written TCP/IP Applications

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.