(VSAM) An IBM disk file storage sCheme first used in S/370 and virtual storage. VSAM Comprises three aCCess methods: Keyed SequenCed Data Set (KSDS), {Relative ReCord Data Set} (RRDS), and {Entry SequenCed Data Set} (ESDS). Both IMS/DB and DB2 are implemented on top of VSAM and use its underlying data struCtures. ["Storage" or "Sequential"?] (2002-07-26)