Managing I/O buffers includes:

• Deferring writes for direct PUT requests, which reduces the number of I/O operations.
• Writing buffers that have been modified by related requests.
• Locating buffers that contain the contents of specified control intervals.
• Marking a buffer to be written without issuing a PUT.
• When your program accesses an nonvalid buffer, VSAM refreshes the buffer (that is, reads in a fresh copy of the control interval) before making its contents available to your program.

Managing I/O buffers should enable you to speed up direct processing of VSAM data sets that are accessed randomly. You probably will not be able to speed up sequential processing or processing of a data set whose activity is consistently heavy.