I usually write:

'#define N 1000000

vector adj[N];

But when I run it locally, I get segmentation fault due to stack size being too small, so I end up reducing N to something like 10000 and forget to change it back again before submitting, causing unnecessary penalties.

So is there anyway to permanently increase stack size in ubuntu?

g++ -Wl,--stack=268435456 file.cpp works in Windows.

ulimit -s unlimited only increases stack size for the specific terminal