Online Documentation for SQL Manager for Oracle
Creating/editing rollback segment
Use the Rollback Segment tab of Rollback Segment Editor to create/edit a rollback segment and specify its properties.
Specify the name of the rollback segment to be created, or view the name of the rollback segment being edited.
Use the drop-down list to select the tablespace in which the rollback segment is created.
Enable the option to indicate that the rollback segment is public and is available to any instance.
Check the option to bring the rollback segment online, making it available for transactions by your instance.
The Storage group lets you specify storage characteristics for the rollback segment: Initial size, Next size, Optimal size, Minimal number, Maximum number.
For more information see Storage attributes.