how to recreate undo tablespace in 19c?

hi,

how to recreate undo tablespace in 19c, for my pdb?

Single tenant database, i.e. one pdb, Database 19c 19.4.0.0, one Linux 7

Local undo management is off I believe, see below

SQL> SELECT property_name, property_value FROM database_properties WHERE property_name = 'LOCAL_UNDO_ENABLED';

no rows selected

I have three undo tablespaces, I'm assuming one of them is for cdb , one for seed and one for the pdb. I inherited this test environment (for context)

SQL>

CON_NAME
------------------------------
CDB$ROOT

SQL> set pagesize 1000
SQL> r
1 select a.tablespace_name, SIZEMB, USAGEMB, (SIZEMB - USAGEMB) FREEMB
2 from (select sum(bytes) / 1024 / 1024 SIZEMB, b.tablespace_name
3 from dba_data_files a, dba_tablespaces b
4 where a.tablespace_name = b.tablespace_name
5 and b.contents = 'UNDO'
6 group by b.tablespace_name) a,
7 (select c.tablespace_name, sum(bytes) / 1024 / 1024 USAGEMB
8 from DBA_UNDO_EXTENTS c
9 where status <> 'EXPIRED'
10 group by c.tablespace_name) b
11* where a.tablespace_name = b.tablespace_name

TABLESPACE_NAME SIZEMB USAGEMB FREEMB
------------------------------ ---------- ---------- ----------
UNDOTBS2 12990 225.375 12764.625
UNDOTBS1 11655 262.3125 11392.6875
UNDOTBS3 17500 608.5625 16891.4375