Acknowledgments

This book captures knowledge that lives primarily in the heads of working mainframe professionals --- the systems programmers, DB2 database administrators, CICS architects, batch operations specialists, and security administrators who built and maintain the transaction processing systems that the global economy depends on. They did not write this book, but everything in it comes from the work they have done, the problems they have solved, and the lessons they learned the hard way. This book is an attempt to ensure that their expertise survives their careers.

We are indebted to the IBM Corporation for decades of technical documentation. The Enterprise COBOL for z/OS Programming Guide (SC27-1412), the DB2 for z/OS SQL Reference, the CICS Transaction Server Information Center, the z/OS MVS JCL Reference, the IBM MQ Programming Guide, and the z/OS MVS System Programming library are the canonical references that underpin every chapter. The IBM Redbook series, particularly those covering Parallel Sysplex, DB2 performance, and CICS architecture, provided depth that no other source matches.

We acknowledge the open-source community that made this book's distribution possible. The mdBook build system, the Creative Commons licensing framework, and the culture of sharing technical knowledge freely are what allow a work of this scope to reach every mainframe professional who needs it, regardless of their employer's training budget.

We thank the readers of Books 1 and 2 in the DataField.Dev COBOL trilogy. Their questions, corrections, and requests for advanced coverage shaped the scope of this volume. The most common request was simple: "Go deeper." We have.

Finally, we acknowledge the mainframe itself --- the platform that processes 95% of ATM transactions, runs the core systems of every Fortune 100 bank, and has maintained continuous availability through half a century of technological change. The z/Architecture is the most reliable, secure, and high-throughput general-purpose computing platform ever engineered. This book teaches you to use it at the level it deserves.