#!/usr/local/bin/perl

$re = qr@
             \{
             (?:
                (?> [^{}]+ )    # Non-{} without backtracking
              |
                (??{ $re })     # Group with matching {}
             )*
             \}
          @x;

my $string = 'value:patternList = "{error 1 1 {^E 0-20-9:0-50-9:0-50-9.*$} {^E 0-20-9:0-50-9:0-50-9.*$}} {three 1 1 {^.*35=A.*$|^.*35=5.*$} {^.*35=A.*$|^.*35=5.*$}} {fixv 1 1 ^.*VFIXFxProxy.*Disconnected ^.*VFIXFxProxy.*Disconnected}"';

while($string =~ m/$re/g){
    print "$&\n";
}

exit;

__END__

output:
{error 1 1 {^E 0-20-9:0-50-9:0-50-9.*$} {^E 0-20-9:0-50-9:0-50-9.*$}}
{three 1 1 {^.*35=A.*$|^.*35=5.*$} {^.*35=A.*$|^.*35=5.*$}}
{fixv 1 1 ^.*VFIXFxProxy.*Disconnected ^.*VFIXFxProxy.*Disconnected}