This configuration variable can be used in conjunction with the A_SORT_REGIONS configuration variable.
If A_SORT_REGIONS is set to a value of 2 or more, you can set this variable to a value between 1 and the value of A_SORT_REGIONS. The default for this variable is 1; also, this variable has no effect if A_SORT_REGIONS is set to 0 (zero).
The value of this variable determines how many sorted regions remain in the temporary sort file before the sort process moves onto the output phase; for example, if A_SORT_REGIONS_FINAL is set to 1, then all the records are merged into a single sorted region before moving to the output phase. When set to a non-zero value, there will be up to that many sorted regions left in the temporary file before moving to the output phase. If there is more than one region left, the remaining regions will be merged during the output phase, similar to the way that the SORT is processed when A_SORT_REGIONS=0. If you are having acceptable performance with a non-zero A_SORT_REGIONS setting, then you can safely leave A_SORT_REGIONS_FINAL at its default setting of 1. This variable is mainly for experimentation, allowing you to increase or decrease the value until you find the best performance.