Abstract: A method and program product to selectively retain or discard subpool expansions. When a subpool has been tuned to its limit (a maximum extension size is established), then a subsequent expansion allocation of this tuned expansion is queued on top of a memory subpool. Otherwise, expansions are queued on the bottom of the subpool. All expansions other than the topmost one, which is retained by the system, are rapidly returned to the system when their storage is no longer needed by the various processes that have finished. The topmost expansion is retained as long as the subpool remains tuned to the maximum extension size. By permitting the topmost expansion to remain available to the subpool for storage allocation, the topmost expansion is retained beyond a short term period typical of expansions, which allows the topmost expansion to stay around for a sufficient time to prevent subpool thrashing.

Abstract: The present invention discloses a solution to selectively retain or discard subpool expansions. In the solution, when a subpool has been tuned to its limit (a maximum extension size is established), then a subsequent expansion allocation of this tuned limited is queued on top of a memory subpool. Otherwise, expansions are queued on bottom of the subpool. All expansions other than the topmost one, which is retained by the system, are rapidly returned to the system when their storage is no longer needed by the various processes that have finished. The topmost expansion is retained as long as the subpool remains tuned to the maximum extension size. By permitting the topmost expansion to remain available to the subpool for storage allocation, the topmost expansion is retained beyond a short term period typical of expansions, which allows the topmost expansion to stay around for a sufficient time to prevent subpool thrashing.