How to increase filedescriptors for Squid?

[Igor Avdeyev]

FREESCO 0.4.2
The problem is there are too little filedescriptors available for Squid. Only 256.
Sometimes, Squid drop requests and there is message in log - "WARNING! Your cache is running out of filedescriptors"
I've found a topic with similar problem:
http://freesco.org/support-forum/viewtopic.php?f=15&t=16061

So I download and install kernel kernel-040.586-vipc-cd-triton-power_off
When I run bash and issue a "ulimit -n 512", filedescriptors changed to 512
I also change header in rc_squid #!/bin/sh to #!/pkg/bin/bash
add line "ulimit -n 512" in section str() of rc_squid

squid is running after rc_squid start, but only 256 filedescriptors available for Squid.
What did I do wrong?