System 390 Job Control Language summary

Understanding the Basics of System 390 Job Control Language

In System 390 Job Control Language by Gary DeWard Brown, the author introduces us to the basics of JCL (Job Control Language) which is a scripting language used on IBM mainframe operating systems. The book begins by explaining the purpose of JCL, which is to define and execute jobs on the mainframe. It also covers the structure of a JCL job, including the job card, the execution control statements, and the data control statements.

Brown takes us through the different types of JCL statements, such as job control statements, data definition statements, and procedure control statements. He explains how these statements are used to specify the resources required for a job, such as the program to be executed, the input and output data sets, and the system resources needed.

Advanced Concepts in System 390 Job Control Language

The book then delves deeper into the advanced concepts of JCL. This includes topics like symbolic parameters, conditional execution, and the use of procedures. Brown explains how symbolic parameters can be used to make JCL more flexible and reusable, while conditional execution allows for the execution of specific steps based on certain conditions.

Procedures, as Brown explains, are a way to encapsulate a series of JCL statements into a single unit. This makes it easier to reuse common sets of JCL, leading to more efficient job execution. The author also discusses the use of system symbols and system variables in JCL, which further enhances the flexibility and adaptability of JCL.

Job Scheduling and Output Management in System 390 Job Control Language

In the latter part of the book, Brown covers job scheduling and output management with JCL. He explains how to use the Time Sharing Option (TSO) to submit and manage JCL jobs interactively. He also discusses the use of the Job Entry Subsystem (JES) for batch job processing and job scheduling.

Output management is another crucial aspect of JCL, and Brown provides a comprehensive overview of how to manage output data sets, including how to control the disposition of output data sets and how to manage system and user abends (abnormal ends). He also covers the use of system utilities for managing and manipulating data sets.

Conclusion and Future Prospects in System 390 Job Control Language

In conclusion, System 390 Job Control Language provides a thorough understanding of JCL, from its basic structure to advanced concepts, and its practical applications. The book is an invaluable resource for system programmers, operators, and application programmers working with IBM mainframe systems, as well as for students learning about mainframe computing.

Brown also touches on the future prospects of JCL, discussing its relevance in the modern computing landscape, and its role in the emerging technologies such as cloud computing and big data processing. He emphasizes that, despite the emergence of new technologies, JCL remains a critical skill for anyone working with mainframe systems, due to its unique capabilities and the continued prevalence of mainframes in many large enterprises.