Each actual page inside a pool is configured from a plurality of actual tracks, and each virtual page inside a virtual volume is configured from a plurality of virtual tracks. A storage control apparatus of a mainframe system has management information that includes information denoting a track in which there exists a user record, which is a record including user data (the data used by a host apparatus of a mainframe system). Based on the management information, a controller identifies an actual page that is configured only from tracks that do not comprise the user record, and cancels the allocation of the identified actual page to the virtual page.