application memory limits

Hi,
    I've got a large dynamic semantic dictionary
filling most of my LispWorks MacOS 10.4 application
with adjustable arrays,  which run OK at about
1.6 gigabytes of application memory.

    But when I add dictionary entries above 1.7 gigabytes,
Lispworks dies and take the MacOS 10.4 with it.
Is there a memory allocation bug in Lispworks?
Shouldn't a 32-bit application allocate properly
up to 4 gigabytes?  Especially in a 64-bit OS?

-- Lawrence Au