Existe o limite e as possibilidades das suas máquinas.
HISTFILE="$HOME/.zsh_history"
HISTSIZE=10000000
SAVEHIST=10000000
setopt BANG_HIST # Treat the '!' character specially during expansion.
setopt EXTENDED_HISTORY # Write the history file in the ":start:elapsed;command" format.
setopt INC_APPEND_HISTORY # Write to the history file immediately, not when the shell exits.
setopt SHARE_HISTORY # Share history between all sessions.
setopt HIST_EXPIRE_DUPS_FIRST # Expire duplicate entries first when trimming history.
setopt HIST_IGNORE_DUPS # Don't record an entry that was just recorded again.
setopt HIST_IGNORE_ALL_DUPS # Delete old recorded entry if new entry is a duplicate.
setopt HIST_FIND_NO_DUPS # Do not display a line previously found.
setopt HIST_IGNORE_SPACE # Don't record an entry starting with a space.
setopt HIST_SAVE_NO_DUPS # Don't write duplicate entries in the history file.
setopt HIST_REDUCE_BLANKS # Remove superfluous blanks before recording entry.
setopt HIST_VERIFY # Don't execute immediately upon history expansion.
setopt HIST_BEEP # Beep when accessing nonexistent history.
You should determine how much memory you have, how much of it you can allow to be occupied by the history (AFAIK it is always fully loaded into memory) and act accordingly. Removing the limit is not wiser as it leaves you with an idea that there is no limit while it is always limited by available resources.
Or if you do not think you will ever hit a problem with resource exhaustion you can just set HISTSIZE to LONG_MAX from limits.h: it is the maximum number HISTSIZE can have.
O que explica a solução do Gentoo:
export HISTSIZE=2000
export HISTFILE="$HOME/.history"
O histórico não será salvo sem o seguinte comando:
export SAVEHIST=$HISTSIZE
Para impedir que o histórico grave entradas duplicadas (como ls -l digitado várias vezes durante uma única sessão de shell), você pode definir a opção hist_ignore_all_dups:
setopt hist_ignore_all_dups
Um truque útil para impedir que determinadas entradas sejam gravadas em um histórico, precedendo-as com pelo menos um espaço.
setopt hist_ignore_space