Out Out Memory

Hi!
I tried to start a java application on a openSUSE 10.2 server. The application needs lots of memory, so I had to start java with the "-Xmx2048m" option. But java doesn't start at all, but gives the following error message:

Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.

Ok, not enough memory available. But "free" says:

> free -m
******** total****** used****** free**** shared****buffers**** cached
Mem:******7987****** 4188****** 3799**********0**********0****** 3562
-/+ buffers/cache:****625****** 7362
Swap:**** 2055**********0****** 2055

And "ulimit":

> ulimit -m -v
max memory size******** (kbytes, -m) 6952745
virtual memory**********(kbytes, -v) 8227280

So what's wrong here?
I tried "strace /usr/java/jdk1.5.0/bin/java -Xmx2048m ..." and found that the critical function call is this:

mmap2(NULL, 2214592512, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0xff92e30c) = -1 ENOMEM (Cannot allocate memory)

But why?

The machine has two Dual-Core-Xeon processors. The kernel is 64bit:

> uname -a
Linux db1 2.6.18.8-0.9-default #1 SMP Sun Feb 10 22:48:05 UTC 2008 x86_64 x86_64 x86_64 GNU/Linux

Can anybody give me a hint?

Thanks a lot,
Christian

P.S.: It's really cute to be a "baby tux"!