Anonymous Monk,
As has already been indicated, the way to create a master array is my @master = (@array1, @array2, @array3); With that said, if the only reason you are doing that is so that you can loop over all 3, then the following works just fine:

my (@array1, @array2, @array3); # defined elsewhere
for ( @array1, @array2, @array3 ) {
    # do something with $_
}
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