[magick-users] why montage with -frame reduce width and hight of my image

[Vu The Cuong]

Hi,
montage displace.png -frame 5 -shadow adorn_montage1.jpg
I'm trying above montage command. I realized that the original image had
width 1024
and heght is 768. 
After ran the command, adorn_montage1.jpg only have width 142
and heght is 140. 
How can I keep width and height as same as original one when using this
command?
Regards