What is Mainframe?
The mainframe is the backbone of many industries that are the lifeblood of the global economy. More mainframe processing power is being shipped now than has ever been shipped. Businesses that require unparalleled security,
availability, and reliability for their “bet your business” applications depend on the IBM zSeries® mainframe,
which runs the z/OS operating system and is protected by the IBM Resource Access Control Facility (RACF).
In this book, we explain the basics of z/OS, focusing on z/OS security and RACF. This chapter describes the evolution of the mainframe and the reasons it is the leading platform for reliable computing. It also explains how to use the key elements of z/OS.