VSAM stands for Virtual Storage Access Method. VSAM is a file storage access method used in MVS, ZOS and OS/390 operating systems. It was introduced by IBM in 1970's. It is a high performance access method used to organize data in form of files in Mainframes. VSAM is used by COBOL and CICS in Mainframes to store and retrieve data. VSAM makes it easier for application programs to execute an input-output operation.
