The object size is the net size of an object (in bytes) in the SAP liveCache basis layer. The actual memory usage of an object is the total of the object size and the header information of the object (24 B). The header contains status information, such as, the time stamp of the consistent view, lock entries, and so on.
The container size can be displayed from the following user menus:
DBA Cockpit, Class Containers
liveCache Assistant, Class Containers
Glossary, Consistent View