increase memory size on Unix

Is there any way I can increase memory size for R under Unix?  I tried Memory 
function, which was not working.

Possibly because there is no Memory function.

The standard configuration of R under Unix uses all the memory the 
operating system will give it.  If your computer is set up this way then 
you probably cannot increase the memory size as an R user.  It is possible 
that your computer administrator may be able to increase the memory size 
that the operating system provides by changing quotas or swap space or 
something.

On the other hand, running out of memory now often means hitting the 
address space limits of 32-bit systems, which can't be solved in software.

 	-thomas