This is not so much a reference book on JCL as an in depth introduction to mainframe JCL that also serve as a reference. This book would make an ideal addition to the library of any novice to intermediate mainframe operator or programmer.
For someone wanting to learn how to write mainframe JCL using MVS, OS/390, or z/OS this book contains everything you need to know and more presented in a logical order that introduces all of the basic concepts first followed by the more complex areas of VSAM file processing, utility programs, and finally associated areas such as TSO, CLIST, REXX, and UNIX system services. The introduction actually tells you how best to use the book to learn JCL.
If anything the book goes into too much detail with explanations of how mainframe computers handle memory and interact with peripherals such as monitors,, disk drives, andtape drives. While much of this information is interesting if you want to know how computers work, the information supplied goes way beyond that which you need in order to be able to write JCL to interact with those functions.
The later sections of the book are also useful for someone with a basic knowledge of JCL to gain a more indepth understanding of some of the more complex features that are only occasionally needed. In particular the book gives the best explanation that I have seen of how condition codes work that I have come across in any book or manual, making it easy for anyone to gain a proper understanding of this much misunderstood area of JCL.
The book is perhaps not quite so useful to the JCL "expert" looking for a reference that they can use to remind themselves of how to code some of the rarely used JCL options. An appendix lists all of the options available but without descriptions of what the different options do. While most of the options are described earlier in the book there are no references between the entries in that appendix and the corresponding descriptions requiring that you swap from the appendix to the index in order to find out where to find the appropriate description.
This article written by Stephen Chapman, Felgall Pty Ltd.