Expert MVS/XA JCL

Expert MVS/XA JCL by Mani CarathanassisThis is a very concise clear and easy to read book on JCL. My background: In college I used JCL to run my programs, but that was about the extent of that. Since 1981 I have worked in the world of Unix and Windoze. I currently am working on a product (Sun Mainframe Batch Manager) that allows Mainframe users to migrate their entire JCL code base and programs to run on SUN Microsystems UNIX hardware at considerable savings. For this I need to understand and write JCL. (Most of my co-workers already have a mainframe background.)This book can be read cover to cover (mostly how I used it) or it can be used as a reference book. Mr. Carathanassis states that the book is not for beginners, but I haven't used JCL for over 20 years (which makes me a beginner) and I found it easy to read and understand. I do have some basic, but minimal, familiarity with JCL. In spite of the author's claims, the "expert" in the title has to refer more to the quality of instruction rather than the level required of the reader. He has done such a fine job that even relative beginners can use this book to full advantage. Mr. Carathanassis takes the time to explain the basics as he goes along. Furthermore, he has a natural tendency to explicitly and succinctly define new concepts rather than expecting the reader to pick them up by osmosis through examples. This grows out of his intimate familiarity with his subject.Just as a lark, I skipped ahead to Chapter 11, Generation Data Groups, prior to reading chapters 5-10. I wanted to see if Generation Data Groups made sense prior to reading the other background information. As I expected, the explanation was simple and plain enough to readily understand the concept of GDGs without additional information required. However, in his discussion of using DCBs when creating new GDGs with relative names, he did not redefine exactly what DCBs were. The user would have to have read chapters 5 (DD Statements) and 8 (Creating Data Sets) for a complete understanding of this one point. Generally though, each chapter stands by itself for an even slightly experienced user. I found I understood GDGs even though I didn't have a clue what a DCB was. The same was true for BLP.So this book can be read out of order if desired with very little difficulty. However, the order of presentation is so well thought out that I see no benefit in doing so. Cross references are usually forward looking, not back, so it makes more sense to read it in the order it is written.The book dates back to 1989, and the text covers MCS/XA, with a chapter on MVS/ESA. However, due to IBM's backward compatibility, all of the information is still valid. It isn't as if JCL technology moves at the speed of light, or even at the speed of sound. JCL is not a rapidly changing target, so older books can still be quite valuable -- as I believe this one is.I purchased this book used, and decided I would sell it if I didn't like it. It wasn't long before