VSAM supports both Undo and forward recovery logging using two different LogStreams. Connect CDC (SQData) capture uses the CICS VSAM LOGREPLICATE function which logs changes in the form of both before-image and after-images as they are committed by CICS on-line applications.
While the same LogStream can be used for both the online CICS VSAM LOGREPLICATE Function and the batch CISC/VR Replication Logging Function, some installations chose to use two different LogStreams. The CDCzLog Publisher component can manage one or more LogStreams containing change data from both online and batch environments. The default behavior of the publisher is to leave the captured data in the LogStream(s) until Engines often running on other platforms, acknowledge that the published data has been applied to target datastores. At that time the publisher will clean as in remove the data captured from the LogStream.