z/OS and Friends: Optional Features Complete a Compelling and Function-Rich Legacy OS
Following up on his exposition of the 50-plus base elements of z/OS, Joe Gulla dives into the optional features, from the language support like the HLASM Toolkit to data management tools like DFSORT
Editor’s Note: This is the second of two articles to be featured in February as part of the “z/OS and Friends” series.
In my previous article, I wrote that I had never studied an operating system at the elemental level—until now. That previous article was about z/OS built-in base elements, and this one is about the z/OS optional features. I am thrilled that I took on this challenge because the information that I discovered through this systematic exercise has been both interesting and surprising.
Let Me Quickly Recap
z/OS has more than 50 base elements. There is the Base Control Program (BCP) with its 12 named elements, including Job Entry Subsystem (JES). There are also 38 other elements spread across eleven categories. The Base Control Program (BCP) and other z/OS base elements are shown in Figure 1.
Figure 1. z/OS with built-in BCP and elements.
In addition to the many built-in base elements, there are 20 optional features that can be mapped into five categories. These categories include Language Support, Device Support, Security, Systems Management and Data Management. In some cases, the optional features build upon the functionality of a related base element. In others, they are stand-alone, new functionality that will be of interest to some customers and not to others. The “big picture” including the optional features is shown in Figure 2.
Figure 2. Optional features in context .
Details About the Optional Features in Context (h2)
Now that you know the context for the optional features, I’ll get into some of the important details about each of them.
1. Language Support (h3)
Every operating system needs programming languages and other software to make those languages work well with display devices and interwork with other systems and applications. z/OS has both base elements and optional features in this category. The table below discusses the four optional features that make programmers more productive with z/OS.
| Optional Feature | How You Can Use It |
| Graphical Data Display Manager (GDDM)-Presentation Graphics Feature (PGF) | Use PGF to create presentation material in various styles by providing a set of presentation-graphics Application Programming Interface (API) routines that provide simpler alternative base APIs for drawing charts. This feature is related to the base element GDDM. |
| GDDM-REXX | Use this optional feature as a productivity tool that enables programmers to prototype GDDM applications. With it, you can create small routines and utility programs quickly and easily. This feature is also related to the base element GDDM. |
| High Level Assembler (HLASM) Toolkit | Use this optional feature because it provides tools to improve application development, debugging and recovery. It builds upon the base element HLASM. Six major features are discussed here. |
| XL C/C++ (includes Open XL C/C++) | XL C/C++ consists of the XL C/C++ compiler, XL C/C++ application development utilities and mathematical acceleration subsystem libraries. Use this optional feature because it supports embedded Customer Information Control System (CICS) and SQL statements in C/C++ source, which simplifies the operation of C/C++ within CICS and Db2 environments. Open XL C/C++ is also included. It is a no-charge add-on feature for users who have enabled z/OS XL C/C++ on z/OS 2.4 or later. Open XL C/C++ is based on the Low Level Virtual Machine LLVM open-source Clang infrastructure and supports current C/C++ language standards and the latest IBM z16 servers. |
2. Device Support
Built-in device support comes for IBM Direct Access Storage Devices (DASDs); magnetic and optical devices come from base elements. In the case of the Infoprint Server, this optional feature enables the productive use of printers throughout the enterprise.
| Infoprint Server | Use the Infoprint Server to help you print files on z/OS printers from any workstation that has TCP/IP access. This feature consists of the following components: • IP PrintWay basic mode and extended mode • NetSpool • Print Interface • Printer Inventory Manager • Transform Interface • z/OS Infoprint Central |
3. Security
Providing support for secure use of resources is particularly important to z/OS. IBM has built into the OS significant support for a variety of important security techniques and standards. Four optional features extend the security support in z/OS and are discussed below.
| Restricted Use Common Service Area (RUCSA) | Use this optional feature if your installations cannot eliminate user key (8-15) common storage usage. RUCSA provides a means of isolating user key common storage to specific users. By doing so, it controls or eliminates the security risk that is associated with common user key storage. |
| z/OS Security Server Resource Access Control Facility (RACF) | Use Security Server to control access to protected resources. Security Server contains one component named RACF, which uses the limited DES, CDMF, RC 40-bit, RSA and DSA algorithms for encryption. |
| z/OS Authorized Code Scanner (zACS) | Use zACS as it dynamically scans authorized code and provides diagnostic information for subsequent investigation as needed. The zACS feature is entitled when you purchase the separately priced product, IBM Threat Detection for z/OS. |
| z/OS Security Level 3 | Use z/OS Security Level 3 because it provides stronger encryption for z/OS. Stronger encryption generally means greater than 64 bits, which makes the encryption harder to crack. The components in this feature that have greater than 64-bit solutions include: Communications Server Security Level 3, which works with the Communications Server base element to provide stronger encryption. IBM Security Directory Server (TDS) Security Level 3, which works with the IBM TDS base element to provide stronger encryption. This component uses the RC4, TDES, and Advanced Encryption Standard (AES) algorithms for encryption.Network Authentication Service Level 3, which works with the Network Authentication Service component of the Integrated Security Services base element. This component uses the Triple Data Encryption Standard Triple DES (TDES) and AES algorithms for encryption.System Secure Sockets Layer (SSL) Security Level 3, which works with the System SSL component of the Cryptographic Services base. This component uses the RC2/RC4, TDES, and AES algorithms for encryption. |
4. Systems Management
For IT systems, management is a general term that is used for a broad set of activities, like monitoring systems and changing their status as required. Management could also mean restarting systems when they fail or become unresponsive. Over the years, a considerable number of management functions and actions have been automated by software specifically written for that purpose.
| Hardware Configuration Manager (HCM) | Use HCM to manage and configure the physical hardware components of a system as it provides a graphical interface to define and modify hardware settings. |
| IBM z/OS Change Tracker | Use IBM z/OS Change Tracker to identify, manage and audit configuration files. This tool can improve aspects of the change configuration management experience including software management and resiliency. |
| IBM z/OS Workload Interaction Correlator | Use this optional feature to configure System Management Facility (SMF) to collect IBM z/OS Workload Interaction Correlator data. IBM z/OS Workload Interaction Correlator makes it possible for a product, such as middleware or an application, to generate high-frequency, summarized system-wide data. Typically, data is collected about products that run in multiple instances that are distributed across multiple address spaces. These complex product instances are the best use-case for this feature. The data that is generated can be used as input to an analytics engine, such as the IBM z/OS Workload Interaction Navigator. |
| Resource Measurement Facility (RMF) | Use the RMF feature to generate performance reports based on the data that is provided by the z/OS Advanced Data Gatherer feature. |
| System Display and Search Facility (SDSF) | Use SDSF because it provides information to monitor, manage and control z/OS systems. After submitting a job, it is common to use SDSF to review the output for successful completion or to review and correct Job Control Language (JCL) errors. With SDSF, you can display output held in the JES spool area. Instead of printing job output, you can inspect it using SDSF and deleted or print it as needed. |
| z/OS Advanced Data Gatherer | Use the z/OS Advanced Data Gatherer feature to write SMF 70-78 record data into the SMF buffer and to SMF data sets or to a log stream. Additionally, application programs can access and report on collected Monitor II, Monitor III and SMF 70-78 record data by using Sysplex Data Server APIs and z/OS Data Gatherer APIs. |
5. Data Management
Data management is the practice of collecting, processing and using data securely and efficiently for better business outcomes.
| Data Facility Storage Management Subsystem Data Set Services (DFSMSdss) | Use DFSMSdss to copy and move data for backup and recovery and to reduce free-space fragmentation. |
| Data Facility Storage Management Subsystem Hierarchical Storage Manager (DFSMShsm) | Use DFSMShsm to provide automated DASD storage management, including space management for low and inactive data, and availability management for accidental data loss caused by local or site disasters. DFSMShsm can also be used to make effective use of tape media. |
| (Data Facility Storage Management Subsystem Removable Media Manager) DFSMSrmm | Use DFSMSrmm as it helps to manage removable media as one enterprise-wide library across systems that can share DASD. DFSMSrmm also has a client/server function that enables a single enterprise-wide library without the need for shared DASD using the TCP/IP protocol. |
| Data Facility Sort (DFSORT) | Use DFSORT to provide sorting, merging, copying, reporting and analysis of business information. DFSORT also includes the high-performance ICEGENER facility, the versatile ICETOOL utility, symbols and multiple output capabilities with the powerful OUTFIL feature control statement. |
| zEnterprise Data Compression (zEDC) for z/OS | Use this optional feature for previous IBM Z servers as zEDC for z/OS provided exploitation of the zEDC Express adapter for hardware data compression. On the IBM z15 and later servers, the zEDC Express adapter is no longer supported or required. The zEDC compression functions are transferred to the processor chip, which is referred to as IBM Integrated Accelerator for z Enterprise Data Compression. |
We Now Have a Fuller Picture
Through the discussion of the optional features, we can understand them as part of the overall z/OS configuration. Figure 3 combines the Base Control Program and its components, plus the base element and optional features in a category view.
Figure 3. z/OS BCP, base elements and optional feature categories.
What is Next?
I hope you have found this z/OS study interesting and useful. In March, I will have two articles that explore JES by discussing functions of the JES subsystem and JCL in a context I’m calling “the two sides of JES.” My initial focus will be on operational and programming views of the subsystem.