In the IBM Zen world, space management is the process used to ensure that there is enough storage space on the user volumes in order to store your data. This feature performs several different functions.
This system expires data sets that have passed their expiration dates. For non SMS managed data sets, you will specify the expiration date when you allocate the data set. For SMS managed data sets, the expiration date will be controlled by the management class that is associated with the data set. Your helpdesk should be able to tell you which way your data is managed. This system also migrates the data sets that have not been used within a specified period of time. The migrated data set is one that has been moved either to tape of to another volume in order to save on space. However, you cannot use a migrated data set directly. But, there is a command that you can issue that will return the data set to a volume where you are able to access and use the data again. These techniques that were developed by IBM will allow you to save a considerable amount on space, as well as manage the space that is utilized by your end users.