C++ Memory allocation

[group . JQ]

Hello:

     I was told that when we allocate the memory (new) at first time
in c++, the c++ library will allocate a big block of memory. Later on,
when we allocate more memory, the c++ library just allocates them from
that big block of memory instead of getting from the operating system.
I wonder if it is possible to specify the size of this memory block?

Thanks a lot.