procedure TForm1.Button1Click(Sender: TObject);
  type
    TMyRec = record
    i1, i2, i3: Integer;
  end;
  TMyArr = array[1..20000000] of TMyRec;
  PMyArr=^TMyArr;
var
  A: PMyArr;
begin
  GetMem(A, SizeOf(TMyArr));
  A^[1].i1 := 100;
  ShowMessage('Ok' + IntToStr(A^[1].i1));
  FreeMem(A);
end;