[PUBLIC]: An optional clause that only has meaning when you are running Parallel Server
segment_name: The name of the rollback segment
tablespace_name: The name of the tablespace where you want to store the rollback segment
INITIAL integer: Specifies the size of initial extent to be allocated for the rollback segment
NEXT integer: Specifies the size of any subsequent extents that are allocated to the rollback segment
MINEXTENTS: Specifies the number of extents to initially allocate when the rollback segment is created. This must be at least two. Rollback segments must always have at least two extents.
MAXEXTENTS: Specifies an upper limit on the number of extents that a rollback segment may have
OPTIMAL: Tells Oracle8 the number of extents that you would prefer the rollback segment to have
