very long string and Segmentation fault

[zychp@o2.pl]

Hello,

I have problem with creating very long strings. When I try to create
string bigger than 5MB I get  Segmentation fault.

Tmp: String_Access;
...
Tmp := new String (1 .. 10_000_000);

In this line a get  Segmentation fault. I use GNAT 3.4.5.

What is more when I run this code:

   type ttt is array (positive range <> ) of Character;
   type ttt_a is access ttt;
   Tmp : ttt_a ;
begin
   Tmp := new ttt ( 1 .. 10_000_000 ) ;
   for i in Tmp'range loop
      Tmp(i) := 'x';
   end loop;

It works fine. But now it's hard to use some Ada.Strings.Fixed
functions.

What can be the reason of this? How it can be soved?

Regards
    Gorion

P.S. I have to use pure Strings (no Unbounded_String etc. ).