You really probably want to be using my instead, because local isn't what most people think of as "local". See "Private Variables via my()" in perlsub for details.
A local modifies the listed variables to be local to the enclosing block, file, or eval. If more than one value is listed, the list must be placed in parentheses. See "Temporary Values via local()" in perlsub for details, including issues with tied arrays and hashes.
The delete local EXPR construct can also be used to localize the deletion of array/hash elements to the current block. See "Localized deletion of elements of composite types" in perlsub.