Apache2. Размер стека и pcre.recursion_limit

Для начала в конфиге PHP необходимо указать значение pcre.recursion_limit :

pcre.recursion_limit = 100000

sysvinit

nano /etc/ini.t/httpd

start() {
  echo -n $"Starting $prog: "
  ulimit -s unlimited
  LANG=$HTTPD_LANG daemon --pidfile=${pidfile} $httpd $OPTIONS
  RETVAL=$?
  echo
  [ $RETVAL = 0 ] && touch ${lockfile}
  return $RETVAL
}

systemd

mkdir -p /etc/systemd/system/httpd.service.d
nano /etc/systemd/system/httpd.service.d/limit.conf

[Service]
LimitSTACK=infinity

systemctl daemon-reload
systemctl stop httpd
systemctl start httpd