The applheapsz configuration parameter
refers to the total amount of application memory that can be consumed
by the entire application.
In versions of DB2® prior
to Version 9.5, the applheapsz database configuration
parameter referred to the amount of application memory each individual
database agent working for that application could consume.
With
Version 9.5, this database configuration parameter has a default value
of AUTOMATIC, meaning that it increases as needed
until either the appl_memory limit is reached,
or the instance_memory limit is reached. For partitioned database environments,
Concentrator, or SMP configurations, this means that the applheapsz value
used in previous releases might need to be increased under similar
workloads, unless the AUTOMATIC setting is used.
- Configuration type
- Database
- Parameter type
- Configurable online
- Configurable by member in a DB2 pureScale® environment
- Default [range]
- Automatic [16 - 60 000]
Note: The default value is subject to change by the DB2 Configuration Advisor after
initial database creation.
- Unit of measure
- Pages (4 KB)
- When allocated
- When an application associates with, or connects to, a database.
- When freed
- When the application disassociates or disconnects from the database.
Note: This parameter defines the maximum size of the
application heap. One application heap is allocated per database application
when the application first connects with the database. The heap is
shared by all database agents working for that application. (In previous
releases, each database agent allocated its own application heap.)
Memory is allocated from the application heap as needed to process
the application, up to the limit specified by this parameter. When
set to
AUTOMATIC, the application heap is allowed
to grow as needed up to either the
appl_memory limit
for the database, or the
instance_memory limit
for the database partition. The entire application heap is freed when
the application disconnects with the database.
The online changed
value takes effect at an application connection boundary, that is,
after it is changed dynamically, currently connected applications
still use the old value, but all newly connected applications will
use the new value.