The default for WebSphere MQ is circular logging. If you do not specify otherwise, when you create a queue manager it will have circular logging invoked.
Changing the type of logging in the qm.ini after queue manager has been created will not change the way the queue manager handles logging. If you wish to convert from circular to linear or vice versa, you would have to recreate the queue manager specifying the new type of logging at creation time.
Linear logging allows you to recreate lost or damaged data... [More]