How to get entire key in one column in gnuplot

I have a long list of keys in my gnuplot graph and , thus, it automatically breaks off into two columns. I want the entire key in 1 column. I tried :

set key maxcols 1

For some reason the command is having no effect even though maxrows command seems to work. Why is the maxcols command not working and is there any other way to achieve the keys in one column?

>Solution :

Version 5.4: set key horizontal maxcol 1

Version 5.5: set key columns 1