In general, the server locks an object to prevent an update operation while the server saves it. If the server cannot obtain a lock on an object within the specified time, the server does not save that object and the server sends a message to the joblog. The save-while-active function shortens the time during which the server locks an object while saving.
Lock Type Needed for Save Operation shows the type of lock the server must obtain successfully to save an object or to establish a checkpoint for the object for save-while-active processing.
When you specify multiple libraries for a save procedure, the server locks the libraries that you specified and the libraries are unavailable for use during the save operation. Some or all of the libraries may be unavailable for use at any given moment.