Cannot Get date displayed correctly in stored procedure

Database

Cannot Get date displayed correctly in stored procedure

I am currently trying to pass a date through a stored procedure as straight sql for this is not possible due to poor performance. The procedure is as follows:

REPLACE PROCEDURE SYSDBA.DATA_PURGE()
BEGIN
DECLARE IN_DT DATE;

SET IN_DT = DATE-398;
LOCKING EDW.PROC_INV FOR ACCESS
INSERT INTO EDW.PROC_INV
SEL * FROM EDW.PROC_INV
WHERE CAST(PROC_DT AS DATE) <= :IN_DT;
END;

After I call the procedure and it is executing, I can see it on the monitor but the sql is displayed as follows:

USING
_spVV1 (DATE)LOCKING TABLE EDW.PROC_INV ACCESS INSERT INTO BKP_EDW.PROC_INV SELECT * FROM EDW.PROC_INV
WHERE (CAST((PROC_DT ) AS DATE))<= :_spVV1 ;

What I really want to see is the exact date. Performance on this is very poor if I used date-398 in a bteq script or macro.
Is this the correct way to get the date-398 displayed into a true date?