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Changing Existing BSAM and QSAM Applications z/OS DFSMS Using Data Sets SC23-6855-00 |
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For existing BSAM, and QSAM applications, in most cases, programs do not have to be changed or recompiled to take advantage of sequential data striping. However, you can choose to update programs to more fully exploit new functions. To improve performance, you will want to have more buffers. You also can have the buffers be above the 16 MB line. If you use BSAM, you can set a larger NCP value or have the system calculate an NCP value by means of the DCBE macro MULTSDN parameter. You can also request accumulation by means of the DCBE macro MULTACC parameter. DCBENSTR in the DCBE macro tells the number of stripes for the current data set. If you use QSAM, you can request more buffers using the BUFNO parameter. Your program can calculate BUFNO according to the number of stripes. Your program can test DCBENSTR in the DCBE during the DCB open exit routine. Existing programs need to be changed and reassembled if you want
any of the following:
Related reading: For more information, see DASD and Tape Performance and the DCBE and IHADCBE macros in z/OS DFSMS Macro Instructions for Data Sets. |
Copyright IBM Corporation 1990, 2014
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