There are two basic pieces of information that one should be able to obtain from the data set name:

1.Who owns it?

2.What is it?

The following section will highlight all of the basic components that could potentially be used in a data set naming standard.

C.2 Components of a Data Set Name

Not all of the following levels of qualification are necessary for naming data sets. Instead, these represent some common levels of qualification that one tends to find in a good and meaningful data set naming convention. Some of the qualifications make sense for certain types of data while other levels don¢t. This list is intended to be a superset of all possible types of qualification levels.

Also, not all of these levels have to be coded as a separate level of qualification (that is, separated by periods). Other possibilities are via positional characters within a given qualifier. The one exception to this is the High-Level Qualifier (HLQ). You should not create unnecessary numbers of these due to positional characters. This is explained in more detail in the next section.

C.2.1 High-Level Qualifier (HLQ)

The HLQ should identify who ²owns² the data. This could be for things such as billing purposes, or simply for locating the owner in case of a problem. It may represent a user ID, a project, an application, a business unit or a group. It may also represent a sharing of the same set of data by a set of individuals from a security standpoint (for example, as the notion of RACF userid and groupid).

There should be no other levels of qualification imbedded in this portion that would tend to artificially multiply the number of HLQs in an installation. The goal should always be to minimize the number of HLQs to the point that they serve the management purpose (that is, billing, identification and so on).

It may be important to even have a standard convention within the HLQ. For example, all TSO user IDs begin with a ²$² as the first character -- this would allow the Storage Administrator to easily avoid filter collisions in ACS Routines. Again, the goal of doing this would be to allow the Storage Administrator to do his job more easily in that all TSO data could be simply filtered out. The trade-off here, of course, would be with the usability of the TSO LOGON IDs.

Another trade-off would be the intent of managing groups of application data. It may be more important, for example, to associate certain TSO LOGONs with the particular application area so that large applications could easily be identified and moved by filtering on the first character of the HLQ. There is also a usability problem here in that the TSO user would have to keep changing his ID if his job changed from one large application to another. This also means that electronic mail might be a problem if individual users have a lot of LOGON ID changes -- this also has some security implications as well (electronic mail being sent to the wrong ID).

Note: As a personal recommendation from the author, it has been found that one tends to cause more problems by choosing user IDs that will definitely change due to such things as career changes. A better way is to have

544VSE to OS/390 Migration Workbook

Page 568
Image 568
IBM OS/390 manual Components of a Data Set Name, High-Level Qualifier HLQ

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.