OMEGAMON z/OS users will often use OMEGAMON to track and analyze resource usage and status inside the z/OS coupling facility (i.e. the CF). There has been a recent chnage to how this information is calculated and displayed in OMEGAMON z/OS. With UA67458 applied, the Utilized Storage Size now shows the 'in use' percent of the total allocated objects (entries and data elements) for the structure.
Here's a link to a technote that discusses this a little more detail.