If you are running BTS in a sysplex, the activities that make up a process may run on different CICS® regions. If you want to use audit logging, you should ensure that audit records can be written to a single logstream from any region that any of the activities run on.
If the CICS regions are in the same MVS™ image, you can define the logstream to use either a coupling facility structure or DASD-only logging. However, if the CICS regions are on different MVS images, the logstream should use a coupling facility structure rather than DASD-only logging. This is because CICS regions on different MVS images cannot access the same DASD-only logstream at the same time.
If the regions are in different MVS images and you use DASD-only logging, you will not be able to use shared logstreams for your BTS logs. This means that audit records for a single process may be split across several logstreams; you will have to collate them yourself.