The virtual lookaside facility (VLF) is a set of MVS™ services that provide a high-performance alternate path method of retrieving named objects from DASD on behalf of many users. VLF is designed primarily to improve the response time for such applications.

VLF uses data spaces to hold data objects in virtual storage as an alternative to repeatedly retrieving the data from DASD. If you have an existing data retrieval application or are considering designing one, determine whether VLF can meet your needs.