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  SAS Institute logo.    Use of Buffers with files.


When reading or writing files, consider increasing the size of the buffers available to the file using the BUFNO= option, or the BUFNI=, and BUFND= options for VSAM files.
The actual amount of buffers to specify varies with the size of the input data, so some amount of experimentation (with a small number of records) may be worthwhile. For the BUFNO option against the Inventory file for example, a value of 15 to 20 seems to work well. For the Master file, the “recommended” values are 5 for BUFNI (if reading the file using keyed reads) and 15 for BUFND.
The buffer values are specified against the DD statement.

e.g.     //GENBASE  DD DSN=FTMP.CSS.GENEXT.BASE.RES.D199904,DISP=SHR,BUFNO=20

If anyone has any more experience of using these options (or anything similar), please add comments here. The use of these options can slow down processing as easily as speed it up, so previous experience is more than helpful.