Cant connect if -B 1024 was set to postmaster

Greetings,

    There are a very weird problem here.

  I changed my /etc/rc.d/init.d/postgresql. The postmaster line now is :
su -l postgres -c "/usr/bin/pg_ctl -o '-B 1024' -D $PGDATA -p
/usr/bin/postmaster start >/dev/null 2>&1" < /dev/null

  That mean now are 8Mb (1024 buffers of 8Kb) available for postgres
processes. Ok, but if I set this '-B 1024' all my non-local connections
don't work. Then, If I simply remove this -B statement everything work
again. Besides, there are lots of -B configurations simply dont work here,
like -B 2048, -B 4096... when I try to call /etc/rc.d/init.d/postgressql
start, it checks installation (ok), but postmaster fails.

Do you know why this is happening?

I'm using RedHat 6.2, AMD K6 400, 256Mb RAM with Postgre 7.0.2.
and a Pentium 75, 32Mb RAM, RedHat 6.2 with Postgre 7.0.3 and both has the
same problem.

Regards,

José Vilson de Mello de Farias