As a control program, z/Virtual Machine (z/VM®) is a hypervisor because it runs other operating systems in the virtual machines it creates.

Any of the IBM® mainframe operating systems such as z/OS®, Linux® for zSeries®, z/VSE™, and z/TPF can be run as guest systems in their own virtual machines, and z/VM can run any combination of guest systems.

z/VM has two basic components: a control program (CP) and a single-user operating system, CMS. The control program artificially creates multiple virtual machines from the real hardware resources. To end users, it appears as if they have dedicated use of the shared real resources. The shared real resources include printers, disk storage devices, and the CPU. The control program ensures data and application security among the guest systems. The real hardware can be shared among the guests, or dedicated to a single guest for performance reasons. The system programmer allocates the real devices among the guests. For most customers, the use of guest systems avoids the need for larger hardware configurations.

z/VM's other major component is the Conversational Monitor System or CMS. This component of z/VM runs in a virtual machine and provides both an interactive end-user interface and the general z/VM application programming interface.