How to log while launching screen

[Joy]

Hi,

I'm using screen as serial console terminal. The command I've used is

/usr/bin/screen -h 65536 /dev/cu.usbserial-00002026C 115200

It works fine, but I want to capture all I've typed and outputs from it 
into a file.

It looks -L or -l option would make it, but it doesn't seem to work for me.

I'm a learning user for unix/linux as well, so if you instruct me how I 
could capture the outputs (especially, automatically) from screen it, it 
would be appreciated. Actually, I'm using Mac OS X 10.6.

Thanks,
Joy