How to stop ZSH from merging history for all closing tabs?

I use combination of zsh with oh-my-zsh and iTerm2 for development on Mac. I'm frustrated with the following issue:

• N tabs opened
• close the terminal
• reopen it (with Use system Window Restoration Setting)
• the history from all previously opened tabs got merged into one for every reopened tab

The question: How to preserve separated history for every reopened tab?

Per https://github.com/robbyrussell/oh-my-zsh/issues/2537,

Add unsetopt share_history to your .zshrc file.