Using striped extended-format QSAM data sets

A striped extended-format QSAM data set is an extended-format QSAM data set that is spread over multiple volumes, thus allowing parallel data access.

For you to gain the maximum benefit from using QSAM striped data sets, z/OS® DFSMS needs to be able to allocate the required number of buffers above the 16 MB line. When you develop applications that contain files allocated to QSAM striped data sets, follow these guidelines:

• Avoid using a QSAM striped data set for a file that cannot have buffers allocated above the 16 MB line.
• Omit the RESERVE clause in the FILE-CONTROL entry for the file. Doing so lets z/OS DFSMS determine the optimum number of buffers for the data set.
• Compile your program with the DATA(31) and RENT compiler options, and make the program object AMODE 31.
• Specify the ALL31(ON) runtime option if the file is an EXTERNAL file with format-F, format-V, or format-U records.

Note that all striped data sets are extended-format data sets, but not all extended-format data sets are striped.