As you have a date stored in string in the format of DDMMYYYY, first you have to convert it into a real date:
DATE(TO_DATE(date_string, 'DDMMYYYY'))
The result is a binary date and can be converted to any string now...
CHAR(DATE(TO_DATE(date_string, 'DDMMYYYY')), USA)
AS400 has only pre-defined formats, so 'USA' will give you MM/DD/YYYY instead of DD/MM/YYYY...You may try 'EUR' that will give DD.MM.YYYY and than replace . (dot) to / (slash)...
Check other options here:
http://publib.boulder.ibm.com/iseries/v5r2/ic2924/index.htm?info/db2/rbafzmstch2func.htm[
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