sub main_loop {
  local($dbh->{AutoCommit}) = 0;
  ... lots of code here, with multiple returns
}

##</code><code>##

  my $tmp_dbh = $dbh;
  $tmp_dbh->{AutoCommit} = 0;  #BZZT!

##</code><code>##

# Wishful thinking
sub main_loop {
  ... stuff happens ...
} continue { ... oops! I must have returned! }

##</code><code>##

sub main_loop {
 {
   ... stuff happens ...
   ... use 'last' instead of 'return'?
 }
 ... restore settings here
}