Finding tablespace with unlimited maxsize

Hi !

 

I need to find, through sceduled pl/sql job, the autoextend tablespaces for wich maxsize is unlimited.

Now we're using a SELECT in wich WHERE clause has hard-coded the maxsize, like this :
 

SELECT s1.tablespace_name
            FROM ( SELECT tablespace_name, SUM (maxbytes) AS maxbytes
                     FROM dba_data_files
                  GROUP BY tablespace_name) s1
           WHERE s1.maxbytes >= 34359721984;

I think it's not very "transportable". Is there's another way to make it cleaner ?