SFTP upload to Harmattan device fails

SFTP upload of over 4MB package to Harmattan device fails.

Qt creator uploads packages to the directory /tmp/ in device.
"df" shows:
"tmpfs 4096 112 3984 3% /tmp"

There is also a lock screen message shown about low storage space on the device.
I did not find any way to manually configure upload location. 4MB for a maximum
installable application size is way too small as Nokia Store accepts 512MB for
Harmattan applications.