The DBCS Compiler directive makes your COBOL compiler recognize two data categories in which data is stored in DBCS. It does not prevent the use of other data categories; thus you can still use those data categories in which data is stored in SBCS.
Provided you have the necessary hardware support, DBCS data items used in input and output will be recognized and their data displayed and accepted correctly on such devices as screens, keyboard, printers, et cetera.