Performance system values: Machine memory pool size

Specifies the size of the machine memory pool. (QMCHPOOL)

Machine memory pool size, also known as QMCHPOOL, is a member of the performance category of i5/OS™ system values. You can use this system value to specify the size of the machine memory pool. To learn more, keep reading.

Quick reference
Location In iSeries™ Navigator, select your system, > Configuration and Service > System Values > Performance > Memory Pools
Special authority None
Default value 20
Changes take effect Immediately
Lockable No

What can I do with this system value?

Specifies the size of the machine memory pool in megabytes (MB). A memory pool is a logical division of memory (storage) that is reserved for processing a job or group of jobs. The machine memory pool contains highly shared machine and operating system programs. Be careful when changing the size for this memory pool because system performance may be impaired if the memory pool is too small.

The machine-enforced minimum value varies depending on the memory size of the machine. The system automatically increases the actual size of the machine memory pool to the machine-enforced minimum value if you specify a smaller value.

If the system has increased the actual size of the machine memory pool, you can determine the actual machine-enforced minimum value for the machine disk pool (pool 1) in iSeries Navigator by doing the following:

  1. Expand your iSeries server.
  2. Expand Work Management.
  3. Expand Memory Pools.

Where can I get more information about this system value?

To learn more, go to the performance system values overview topic. If you are looking for a specific system value or category of system values, try using the i5/OS system value finder.

Related concepts
System values: Performance overview
Related information
System value finder