Welcome to the Monastery, periodicalcoder!

If the last line of each entry will always be CAS*, you can split up the file into chunks by setting the record separator ($/) to that, then configure your regex to match across newlines (/m) and to match newlines (/s). The zero-width lookahead (?:...) ensures that '00003' comes after "LX*" and before the record separator ("CAS*").

use warnings;
use strict;

open my $fh, '<', 'file.txt' or die $!;

{
    local $/ = 'CAS*';
    while (<$fh>){
        print $_ if /LX\*.*(?=00003$)/ms;
    }
}

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In reply to Re: Matching range of text with another string in between by stevieb
in thread Matching range of text with another string in between by periodicalcoder

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