<http://thread.gmane.org/gmane.comp.gnu.libtool.patches/10643>
Quoting zshall(1):
THE ZSH/PARAMETER MODULE
The zsh/parameter module gives access to some of the internal hash
tables used by the shell by defining some special parameters.
options
The keys for this associative array are the names of the options
that can be set and unset using the setopt and unsetopt
builtins. The value of each key is either the string on if the
option is currently set, or the string off if the option is
unset. Setting a key to one of these strings is like setting or
unsetting the option, respectively. Unsetting a key in this
array is like setting it to the value off.
This lives even after 'emulate sh'. OK to commit?