Вот тут есть информация по разным переменным, по DB2_AWE тоже... Но это для 8 версии.

В 9-ке должны были внести изменения, почитать здесь ...

Вот ещё несколько слов о DB2_AWE.

Windows 32-bit processes can access memory above the 4 Gbyte boundary
imposed by a 32-bit hardware address pointer by using the Microsoft Address
Windows Extensions (AWE). DB2 can address the memory above 4 GB by
setting the DB2_AWE registry variable, and can utilize memory up to 64 GBytes for
buffer pools.

DB2 makes use of a “window” within the process’s user address space to access
memory above 4 GBytes. The size of the window is configurable and must be
between two buffer pool pages and 1.5 GBytes (or 2.5 GBytes, when the /3GB
option is used).

Memory accessed using AWE is associated with one or more buffer pools. The
buffer pool must be defined (that is, it must exist in SYSCAT.BUFFERPOOLS)
before it can be used by AWE. The DB2_AWE registry variable is used to define the
buffer pool, the number of pages in the buffer pool, and the size of the window.
Memory accessed via AWE is also “locked’; that is, it will not get paged out. This
can provide a performance benefit—but be aware that it may affect the
performance of other, non-DB2 processes. The format of the registry variable
setting is as follows:

db2set DB2_AWE=<buffer_pool_id>,number_of_pages, size_of_window

Where buffer_pool_id is the identifier for the buffer pool. This can be found in
the BUFFERPOOLID column of the relevant row in SYSCAT.BUFFERPOOLS. The
buffer pool must have been defined before you define the DB2_AWE variable entry.

The number_of_pages represents the number of pages of “buffer pool page size”
in the memory region, and size_of_window represents the window size in “buffer
pool page size” pages. Thus the region size is:
(number_of_pages+size_of_window)*buffer_pool_page_size bytes.
To define multiple regions, add semi-colon-separated entries, as shown in the
following example:

db2set DB2_AWE=1,100,20;2,500,100

If AWE support is enabled, extended storage cannot be used for any buffer pools.