Unable to reserve memory when launching a 64-bit VxWorks simulator instance using VxSim

I've built a 64-bit VxWorks 6.9 Image Project in Eclipse, using the following settings:

• BSP: simpc
• Address mode: 64-bit
• Tool chain: gnu
• Profile: (no profile)
• Options: SMP support, IPv6 enable kernel libs

When I attempt to launch this VxWorks simulator instance either using vxsim from the VxWorks Development Shell command line or from within Eclipse I get the same error:

Virtual Base Address:  0x0000000180000000
Virtual Top  Address:  0x0000000500000000    Virtual Size: 0x0000000380000000 (14Gb)
Physical Base Address: 0x0000000180000000
Physical Top Address : 0x0000000184000000   Physical Size: 0x0000000004000000 (64Mb)
Error: Unable to reserve memory at addr 0x80000000 (0x10000 bytes) in VxSim  process (error: 0x1e7).

(I have a 64-bit Windows host.)

I have no such problems launching a 32-bit VxWorks 6.9 Image Project.

Any ideas how to solve this memory problem?