Set stack limit permanently in Ubuntu

Question

I need to increase the stack limit on Ubuntu 18.04 permanently, such that the new limit is in place for all users in all circumstances. Thus, setting in with ulimit -s ..., including in Bash profile and similar solutions, will not work for me. I tried:

• Setting the limit in /etc/security/limits.conf. This had no effect. I tried setting both hard and soft limits, for root and my user. Restarted. Nothing changes.
• Set DefaultLimitSTACK=32768 in /etc/systemd/system.conf and /etc/systemd/user.conf. 32768 is the desired stack limit in Kb. The window manager wouldn't load after restart, instead I was dropped into some kind of emergency root shell, where most commands segfaulted as well. I interpreted it as the stack limit being set to 32Kb instead of 32Mb as intended.
• Set DefaultLimitSTACK=33554432 in /etc/systemd/system.conf and /etc/systemd/user.conf. The system loads normally, ulimit -s still shows 8192, nothing changed.

Could someone advise how to make this work? Thank you!

Answer 1

You can try writing a script(where you set the ulimit) in /etc/init.d/ directory.

Syntax of scripts in /etc/init.d/ - https://bash.cyberciti.biz/guide//etc/init.d

These scripts are executed while switching on and off the system [Specific function is called for start and stop].

Answer 2

Firstly systemd ignores parameters set in ulimits, see https://serverfault.com/a/678861

On my Ubuntu 18 system I'm using 16mb stack and set it in /etc/systemd:

user.conf:    DefaultLimitSTACK=16777216

system.conf:  DefaultLimitSTACK=16777216

• System restart or log out of the session for the new settings to take effect. You can then use ulimit -s <value> to set your stack for the user's shell session at or below the DefaultLimitStack.

Additionally you can add ulimit -s 16384 into your user's .bashrc file. Then Each time its session is started the stack will be set to this desired value.