SQL function relay warning

I have a SQL function that monitors for a warning condition. I need it to
relay that warning to the caller. It catches the warning fine, but I can't
get it to relay. The caller gets the NULL but not the SQLSTATE and message
text. I've tried RESIGNAL and SIGNAL.

DECLARE EXIT HANDLER for SQLWARNING
BEGIN
-- Neither RESIGNAL or SIGNAL seems to work.
--RESIGNAL;

--GET DIAGNOSTICS CONDITION 1
-- v_state = RETURNED_SQLSTATE,
-- v_msg = DB2_ORDINAL_TOKEN_4;
--signal sqlstate v_state
-- set message_text = v_msg ;
RETURN null ;
END ;


Any suggestions?