Listener.log is growing fast.

As the listener.log on one of my database is growing fast,(like in one day it increases upto 20 MB) everyday i've to delete the log and restart the listener.
Then i tried to make the listener.log off.
For that I tried following steps:

I've set logging_listener=off in listener.ora
also tried to make log_status=off
But still it's growing.
Can u pls provide proper solution to off the listener.log ? After making log level off, whether it cause any effect to database?

Thanks in advance.

LSNRCTL> show log_status
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
LISTENER parameter "log_status" set to ON
The command completed successfully

See the log status

1. To permanently turn off listener logging, modify the listener.ora and add/change LOGGING_*YOUR_LISTENER_NAME*=OFF

2. To temporarily turn off listener logging, from lsnrctl prompt:
LSNRCTL>SET LOGGING_*YOUR_LISTENER_NAME*=OFF

3. To get the current listener logging status, from lsnrctl prompt:
LSNRCTL>show log_status

Ken

Hi,
Today i've stopped the listener,deleted the previous logs and add parameter logging_listener=off to listener.ora ,so the logging get stopped.
But before that when i gave
LSNRCTL> set logging_listener=off
It says undefined set command.
Why is it so?
Let me know your opinion.

Becuase it is wrong..