Irule help

done some research found below , how i can call the parameters in this particular those 2 value

when RULE_INIT {
  set DEBUG 1
  set sec_http_max_post_data_length 50
}

when HTTP_REQUEST {
  if { [string tolower [HTTP::uri]] equals "/abc/" and [HTTP::method] equals "POST" } {
    set len [HTTP::header "Content-Length"]
      if { [expr $len > $::sec_http_max_post_data_length] } {
        log local0. "  SEC-ALERT: POST Length: uri=[HTTP::uri]; len=$len; max_len=$::sec_http_max_post_data_length"
        reject
      }
    }
  }
}