Database System Monitor Heap Size (mon_heap_sz)

Configuration Type
Database manager

Applies to

Parameter Type
Configurable

Default [Range]

UNIX
56 [ 0 - 60 000 ]

OS/2 and Windows NT Database Server with local and remote clients and Satellite Database Server with local clients
24 [ 0 - 60 000 ]

OS/2 and Windows NT Database Server with local clients
12 [ 0 - 60 000 ]

Unit of Measure
Pages (4KB)

When Allocated
When the database manager is started with the db2start command

When Freed
When the database manager is stopped with the db2stop command

Related Parameters
Default Database System Monitor Switches (dft_monswitches)

This parameter determines the amount of the memory, in pages, to allocate for database system monitor data. Memory is allocated from the monitor heap when you perform database monitoring activities such as taking a snapshot, turning on a monitor switch, resetting a monitor, or activating an event monitor.

A value of zero prevents the database manager from collecting database system monitor data.

Recommendation: The amount of memory required for monitoring activity depends on the number of monitoring applications (applications taking snapshots or event monitors), which switches are set, and the level of database activity.

The following formula provides an approximation of the number of pages required for the monitor heap: 

  ( number of monitoring applications + 1 ) *
  ( number of databases *
    (800 + ( number of tables accessed * 20 )
     + ( ( number of applications connected + 1) *
         (200 + (number of table spaces * 100) ) ) ) )
  / 4096

If the available memory in this heap runs out, one of the following will occur: