Gnat storage size

What command line parameter do I need with Gnat 3.15p to increase the
main program's stack size? I'm getting
raised STORAGE_ERROR : big.adb:4 object too large
when the command line parameter is >= 4026 with the program:
with ada.command_line;
procedure big is
procedure try(k : in integer) is
x : array(1 .. k*1042) of integer;
begin
x(1) := 0;
end try;
begin
try(integer'value(ada.command_line.argument(1)));
end big;
.