Overflow com Aplicativo [ubuntu]

Boa noite
Estou começando em Java, na verdade, atráves de outros aplicativos, analisando reações de overflow, etc.

Uso um aplicativo de servidor numa máquina minha de testes (um web-proxy)
Inicializo assim o aplicativo:

Java -Xmx1024m -Dsun.net.inetaddlr.ttl=0 -jar

Porém quando limito a 1024M ele tem provabilidade de dar erro de overflow, então sempre deixo em 350M

Alguém saberia como seria para resolver isso?

Parte do Log:

VM Arguments:
jvm_args: -Xmx1536m -Dsun.net.inetaddr.ttl=0
java_command: /home/ems.jar
Launcher Type: SUN_STANDARD

Environment Variables:
PATH=/sbin:/usr/sbin:/bin:/usr/bin
LD_LIBRARY_PATH=/usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/amd64/server:/usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/amd64:/usr/lib/jvm/java-6-sun-1.6.0.22/jre/…/lib/amd64

Signal Handlers:
SIGSEGV: [libjvm.so+0x731250], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGBUS: [libjvm.so+0x731250], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGFPE: [libjvm.so+0x5f5e30], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGPIPE: [libjvm.so+0x5f5e30], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGXFSZ: [libjvm.so+0x5f5e30], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGILL: [libjvm.so+0x5f5e30], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGUSR1: SIG_DFL, sa_mask[0]=0x00000000, sa_flags=0x00000000
SIGUSR2: [libjvm.so+0x5f8650], sa_mask[0]=0x00000000, sa_flags=0x10000004
SIGHUP: [libjvm.so+0x5f83a0], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGINT: SIG_IGN, sa_mask[0]=0x00000000, sa_flags=0x00000000
SIGTERM: [libjvm.so+0x5f83a0], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004
SIGQUIT: [libjvm.so+0x5f83a0], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004

--------------- S Y S T E M ---------------

OS:squeeze/sid

uname:Linux 2.6.31-22-generic #68-Ubuntu SMP Tue Oct 26 16:37:17 UTC 2010 x86_64
libc:glibc 2.10.1 NPTL 2.10.1
rlimit: STACK 10240k, CORE 0k, NPROC 118784, NOFILE 1024, AS infinity
load average:6.08 3.97 1.92

CPU:total 2 (2 cores per cpu, 1 threads per core) family 16 model 4 stepping 3, cmov, cx8, fxsr, mmx, sse, sse2, sse3, popcnt, mmxext, 3dnow, 3dnowext, lzcnt, sse4a

Memory: 4k page, physical 14142264k(12468888k free), swap 9936160k(9936160k free)

vm_info: Java HotSpot™ 64-Bit Server VM (17.1-b03) for linux-amd64 JRE (1.6.0_22-b04), built on Sep 15 2010 01:07:59 by “java_re” with gcc 3.2.2 (SuSE Linux)

time: Sun Nov 14 15:38:15 2010
elapsed time: 539 seconds

O log está na limitação de 1024M, quando deixo em 350M não dá esse problema.
Obrigado