HiperPools.....

Are not Part of the DBM1 Address Space
Requires about 2% of Allocated Space in DBM1
- Hash Control Blocks
Up to 8 Gigabytes (4 - 2 Gigabyte ESO Hiperspaces)
Castout = Yes or No
A VP can Map to One or more HiperPools
Additional Threshold ‘HPSEQT’
- HiperPool Space available for Sequential Pages

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Notes:

While we may get lunch included with this conference, there is still no free lunch with DB2. Using Hiperspaces still cost us some space in the DBM1 address space...about 2% of the defined HiperPool size. A 2-Gigabyte HP, requires about 40 Meg of memory in the DBM1 address space for ‘Hash Blocks’ that contain information about all the pages that are in the HP.

Additionally, the HP can be ‘Page Fixed’ in Expanded by using CASTOUT=N. When this is not used, the memory can be stolen by MVS, and pages expected to be found in the HP will not be there. These are HP read ‘misses’.