Well cooked!  Oddly enough, all you need is:    splice @{$vips{$k}{'stack'}}, 0, -50; It will leave the array untouched if it is not greater than 50.

$ perldoc -f splice
   . . .
   If LENGTH is negative, leaves that many elements off the end of the
+ array.
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(I guess they mean "off the deleted array" -- at all events, that's how it works (and also what makes sense).  It's explained clearly here!)

  p