initdb fails

This is running on a Solaris 8 machine.

I installed V 7.4.7 to use with OpenACS.

lcd[34]% /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
...
selecting default max_connections... 10
selecting default shared_buffers... 50
creating configuration files... ok
creating template1 database in /usr/local/pgsql/data/base/1... FATAL:
could not create shared memory segment: Invalid argument
DETAIL: Failed system call was shmget(key=1, size=1081344, 03600).
...

lcd[36]% sysdef -i | grep SHMMAX
1048576 max shared memory segment size (SHMMAX)

-----------
So the shared memory request is greater than the SHMMAX in
the kernel. If I just wanted to use a smaller number of shared_buffers
(24), I tried editing /usr/local/pgsql/data/pgsql.conf.

But initdb -D /usr/local/pgsql/data
finds that the directory is not empty and will not create the databases.
I have also tried
setenv PGOPTIONS="shared_buffers = 24"
and tried initdb, but initdb uses the default number.

Could you tell me how to set shared_buffers from the default so
that a smaller shared memory segment will be requested?

If you could also tell me how to set the max_connections to a value
different from the default, that would be great.

Any advice appreciated.

Anne Hammond, University of Colorado at Boulder