Enable unlimited scrollback with iTerm2 I tried to check Unlimited scrollback option in the iTerm2 settings, however, it doesn't seems to be applied for longer outputs (say couple of thousands lines). The output gets truncated so I can scroll up just to the last 1000 lines or so. 

I am running Mojave with ZSH 5.7.1 installed, the HISTSIZE is set to the 100 000 lines (however I don't think that matters to the terminal emulator). So is there something I am missing? Thanks for help
Unlimited scrollback might not work properly as expected, I am not sure why but it is may be because of the config of zsh. 

So, I would suggest you specify the scrollback lines like 10000 (in my case) in the textbox and unchecked the "unlimited scrollback buffer" option