How IMS Relates to zOS

How IMS Relates to z/OS

IMS is a large application that runs on z/OS. There is a symbiotic relationship between IMS and z/OS. Both are tailored to provide the most efficient use of the hardware and software components.

IMS runs as a z/OS subsystem and uses several address spaces: one controlling address space, several separate address spaces that provide IMS services, and several address spaces that run IMS application programs. z/OS address spaces are sometimes called regions,^[1] as in the IMS control region. The term region is synonymous with a z/OS address space.

^[1] The concept of a region originated in the MVT (Multiprogramming with Variable Number of Tasks) operating system, a precursor to z/OS.

The various components of an IMS system are explained in more detail in "Structure of IMS Subsystems."