As far as I'm aware there should be plenty memory still available. Here is the result for df-h.
Filesystem Size Used Available Use% Mounted on
ubi0:rootfs 456.8M 63.7M 393.2M 14% /
devtmpfs 67.1M 4.0K 67.1M 0% /dev
tmpfs 64.0K 0 64.0K 0% /media
tmpfs 67.2M 268.0K 66.9M 0% /var/volatile