IMS as a Transaction Manager
IBM developed an online component to ICS/DL/I to support data communication access to the databases. The DL/I callable interface was expanded to the online component of the product to enable data communication transparency to the application programs. A message queue function was developed to maintain the integrity of data communication messages and to provide for scheduling of the application programs.
The online component to ICS/DL/I became the Data Communications (DC) function of IMS, which is known today as the IMS Transaction Manager (IMS TM).