time-stamp-time-zone

time-stamp-time-zone is a variable defined in `time-stamp.el'.
Its value is

nil

• This variable is safe as a file local variable if its value
  satisfies the predicate `string-or-null-p'.

Documentation:
If non-nil, a string naming the timezone to be used by M-x time-stamp.
Format is the same as that used by the environment variable TZ on your system.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 20.1 of Emacs.