If only one table space is specified, all table parts are stored in this table space. This clause cannot be specified when creating a subtable (SQLSTATE 42613), because the table space is inherited from the root table of the table hierarchy. If this clause is not specified, a table space for the table is determined as follows:

IF table space IBMDEFAULTGROUP (over which the user
  has USE privilege) exists with sufficient page size
    THEN choose it
ELSE IF a table space (over which the user has USE privilege)
  exists with sufficient page size (see below when
  multiple table spaces qualify)
    THEN choose it
ELSE return an error (SQLSTATE 42727)

If more than one table space is identified by the ELSE IF condition, choose the table space with the smallest sufficient page size. If more than one table space qualifies, choose the table space in the following order of preference, depending on to whom the USE privilege was granted:

   1. The authorization ID
   2. A role to which the authorization ID is granted to
   3. A group to which the authorization ID belongs
   4. A role to which a group the authorization ID belongs is granted to
   5. PUBLIC
   6. A role to which PUBLIC is granted to

If more than one table space still qualifies, the final choice is made by the database manager.
Table space determination can change if:

    * Table spaces are dropped or created
    * USE privileges are granted or revoked