Asynchronous processing is a form of intercommunication in which one transaction initiates another, and the two transactions then run independently of each other (that is, asynchronously).
Asynchronous processing is initiated when a transaction issues a START command for a remote transaction The issue of the START command can be regarded as a special case of function shipping, in which the shipped request is a START command. Data passed by the starting transaction can be accessed by the started transaction using the RETRIEVE command.
A transaction can initiate and communicate synchronously with a remote transaction and then terminate, leaving the initiated transaction to continue asynchronously. The original initiating request can flow in either direction between System/390® and non-System/390 CICS systems.