Abstract The ABCs of IBM® z/OS® System Programming is a 13-volume collection that provides an introduction to the z/OS operating system and the hardware architecture. Whether you are a beginner or an experienced system programmer, the ABCs collection provides the information that you need to start your research into z/OS and related subjects. Whether you want to become more familiar with z/OS in your current environment, or you are evaluating platforms to consolidate your online business applications, the ABCs collection will serve as a powerful technical tool. Volume 1 provides an updated understanding of the software and IBM zSeries architecture, and explains how it is used together with the z/OS operating system. This includes the main components of z/OS needed to customize and install the z/OS operating system. This edition has been significantly updated and revised.