Oracle can have dates and time stamps in a field declared as the Date data type.
This means that you used to have to figure out what was in which fields in DB2.
However, a new set of compatibility features have been introduced to DB2 so that the date data type can be compatible with the oracle data types.
There is also a compatibility feature for varchar and number.
These are set at the database level as parameters.
The documentation is on this page.
https://www.ibm.com/docs/en/db2/9.7?topic=features-introduction-db2-compatibility