Is there a way to return memory to OS?

[Hao Xia]

Hi,

I have some temporary data has to be released and give the memory back to OS. 

I have searched lots of stuff on the web, but it seems that glibc wasn't
designed to do that.

I just hope maybe there are still some special tricky methods able to do this.
I also found on Redhat 7.3 with glibc-2.2.5-34, my test program was working
while on Redhat9 not.

Looking forward to expertise suggestions.

Thanks!
Hao