Maybe this is a repetition of a question already asked--possibly even asked and answered--but having re-read the thread, I cannot see it. So here goes:

{ #outer scope
  $lamb = lambda ( $x, $y, $z ) => sub { $x + $y }
}
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This is, in a sense, the crux of my problem—I don't want the values of $x, $y, and $z to leak from the inside out, or vice versa,

What are you trying to achieve that this doesn't?

my( $x, $y, $z ) = ( 1,2,3 );
my $lamb = do{
    my( $x, $y, $z ) = ( $x, $y, $z );
    lambda ( $x, $y, $z ) => sub { $x + $y }
}
[download]