Are the quantities x, y, z and n known beforehand? You can do most of this with a single unpack call. Some of the values might need to be fixed up after its parsed.

Here's probably how I would go about it:

my ($x, $y, $z, $n, $len) = ... # fill in these parameters

my $format = "V$x n$y n C$z ".("Z$len" x $n);
my $recsize = 4*$x + 2*$y + 2 + $z + ($n*$len);

open B, '<', 'binary_file.bin' or die ...;

while (read(B, $buf, $recsize) == $recsize) {
  my @values = unpack($format, $buf);

  my @x = splice(@values, 0, $x);   # snip off the 4-byte ints
  my @y = splice(@values, 0, $y);   # the 2-byte ints
  my $bits = splice(@values, 0, 1);
  my @z = splice(@values, 0, $z);   # the 1-byte ints
  # @values now contain just the null-terminated strings

  # manually fix up signed vs. unsigned shorts in @y:
  $y[1] -= 65536 if ($y[1] > 32767); # repeat for each signed valued

  ...process the record...
}
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Admittedly, fixing up the shorts is a kludge. Unfortunately, there doesn't seem to be a format for big-endian signed values, so that's why I opted for this approach. I like to use the platform-independent formats n and v for shorts as opposed to the platform-dependent formats s and S to make the code, well, platform-independent.

Update: Fixed format based on alexm's comment.