It's the tablespace's max size which limits the table's max size.If each table partition is in different tablespace,the max size of table is near the sum of every tablespace's max size.
Please see
http://www.ibm.com/developerworks/da....html#capacity
"Larger table capacity: Without partitioning, there are limits on the maximum amount of data a storage object, and hence a table, can hold. However, by dividing the contents of the table into multiple storage objects or data partitions, each capable of supporting as much data as in a non-partitioned table, you can effectively create databases that are virtually unlimited in size."