If naming differences exist, you need not rename your COBOL fields and you need not change the database. This is because the -Fx compiler option builds XFDs that map your COBOL fields to the correct database fields. The mapping is automatic if the names are the same. If the COBOL name differs from the database name, you enable the compiler to make the correct mapping by adding a NAME XFD directive to your COBOL code.
You can also use XFD directives to produce other effects when data is mapped from COBOL to the database. XFD directives are described in detail in Using XFD Directives.