https://www.ibm.com/docs/en/ims/15.4.0?topic=devices-dfsappc-system-service
IMS 15.4 - Communications and connections - DFSAPPC system service
DFSAPPC is an IMS system service for exchanging messages between LU 6.2 application programs (LU 6.2 to LU 6.2), and between LU 6.2 application programs and...
imscommunicationsconnectionssystemservice