column Sname form a40    heading 'Object Name'
column Stype form a15    heading 'Type'
column Size  form 9,999  heading 'Size'
column Next  form 99,999 heading 'Next'
column Tname form a15    heading 'TsName'

select a.owner||'.'||a.segment_name "Sname", 
       a.segment_type               "Stype",
       a.bytes/1024/1024            "Size",
       a.next_extent/1024/1024 "Next", 
       a.tablespace_name "TName"
  from sys.dba_segments a
 where a.tablespace_name not like 'T%MP%'   -- Exclude TEMP tablespaces
   and next_extent * 2 > (                  -- Cannot extend 1x, can change to 2x...
                           select max(b.bytes)
                             from dba_free_space b
                            where a.tablespace_name = b.tablespace_name);