Even when the Automation Engine DB is properly maintained with the Archive, Reorg and Unload Utility (ucybDBAR, ucybDBRE, ucybDBUN), it is possible that the size of the DB LOB Segment keeps growing.
It is a known issue that the reuse of allocated space by LOBs of type BasicFiles is not efficient.
To prevent the LOB segment of the DB from growing the DBA has different options:
1. Regularly reorganization of the LOB Segment
2. Upgrade to Oracle v12c and uses LOB type SecureFiles which is more efficiently reusing free space.