Setting Kernel Parameters

["E. Craig Brown" <ecbrown lanl gov>]

I am trying to change the default values for kernel parameters
rmem_default, rmem_max, wmem_default and wmem_max. I modify the
/etc/sysctl.conf file and add rows:
rmem_default = 262144
rmem_max = 262144
wmem_default = 262144
wmem_max = 262144

In case this looks familiar, I am doing this to install an Oracle
database. I have set the values of other kernel parameters in this way,
however, when I try to set these and execute sysctl -p, these four return
a message of 
error: 'rmem_default' is an unknown key
error: 'rmem_max' is an unknown key
error: 'wmem_default' is an unknown key
error: 'wmem_max' is an unknown key
Do any of you have any ideas as to why these parameters will not
be set? I run the command "/sbin/sysctl -a | grep rmem_default"
and have a message return the current value of each of these as expected.
My guess is that while I am using the specific string that the Oracle
Documentation guide suggests to use to change the values of these
parameters, I probably need a different syntax.
Thank you,
Craig