IMS supports the z/OS CPI-C (Common Programming Interface for Communications) interface, which is based on Logical Unit type 6.2 formats and protocols for program-to-program communication. APPC is an implementation of the LU type 6.2 protocol. IMS's support for APPC is called APPC/IMS.

APPC/IMS enables applications to be distributed throughout an entire network and to communicate with each other regardless of the underlying hardware.