kernel memory issue

Hi Everybody,
                     I am working on Montavista kernel, busybox
utilities...ppc processor I have 32Mb RAM.
Heres the df output below:

# df
Filesystem           1k-blocks      Used Available Use% Mounted on
rootfs                    4068      3234       834  79% /
/dev/ram0                 4068      3234       834  79% /
/dev/fl1                 31968      3009     28959   9% /mnt/fastpath
tmpfs                    11264      7388      3876  66%
/mnt/application
tmpfs                    11264         0     11264   0% /mnt/download
#

I dont know Why I cant download more than 6Mb files on /mnt/download.
It gives, out of memory. Is it the busybox utility problem or should I
go for changing libraries.

Can anybody throw any insight to the problem?