Can't ALTER a column to have a new DEFAULT value.

Documentation states that an existing column in a table can have a DEFAULT value added via the ALTER TABLE statement. Unfortunately, none of the syntax provided gives a way of accomplishing this. An equivalent command from DB2 would be:

ALTER TABLE EMPL ALTER COLUMN BONUS SET DEFAULT 1000;

Is this an error in the documentation, and omission in the product, or is there a different command to accomplish this?