Knowledge Sharing - Advantage of installing BES Domino on a 64-bit edition of Windows
 

Applicable to:

(1) BES Domino 4.1.4 or later
(2) Large deployment with many BlackBerry users
(3) Small/Medium deployment with many heay hard-core BlackBerry users sending/receiving hundreds and thousands of messages per day

[Quote]
Installing the BlackBerry® Enterprise Server software with a 64-bit edition of a Windows® operating system provides access to more virtual memory.

Because the BlackBerry Enterprise Server for IBM Lotus Domino runs as an add-in task to IBM® Lotus® Domino®, the shared memory used by IBM Lotus Domino contributes to the total virtual memory used by the NBES.EXE process. Typically, IBM Lotus Domino uses approximately 1 GB of virtual memory.

The 32-bit editions of Windows only allows 2 GB of virtual address space per process; the NBES.EXE process is left with approximately 1 GB of virtual memory to use. On most computers, this is not a problem. However, with large installations, the 32-bit editions of Windows can cause processes using more than 2 GB of virtual memory to stop responding.

Installing the BlackBerry Enterprise Server software with a 64-bit edition of Windows provides 4 GB of virtual address space. This increases the available virtual memory from approximately 1 GB to approximately 3 GB for the BlackBerry Enterprise Server, and reduces the possibility that the NBES.EXE process will reach the virtual memory limit.

BlackBerry Enterprise Server software version 4.1.4 and later supports installation with 64-bit editions of Windows.

Link: View Document

Yep, that was explained at WES 09 at one of the intros to BES 5.

It is not documented enough.