Today more than ever, businesses depend on the critical data that flows over networks. A large amount of sensitive and confidential data is stored and retrieved from z/OS systems, so the data that moves through z/OS-attached networks must be secured, have high integrity, and be available at all times. The mainframe environment includes both hardware and software tools that meet these goals.

New mainframe hardware and software are ideal for network transactions because they are designed to allow huge numbers of users and applications to access rapidly and simultaneously the same data without interfering with each other. In networks that support thousands of end users, the mainframe concepts of data integrity, security and reliability are extended to include the network.

The designer of a large network must balance the need for data and transaction security with the requirement to provide rapid response time and reliability and availability of the network.

Some of the aspects of security that need to be taken into account are discussed briefly below. This topic is discussed in more detail in the topic on network security.