use strict;
use warnings;

my ($start, $keyword, $end) = ('PROC SQL', 'DELQ_STATUS', 'QUIT');
my  @block;

while (<DATA>)
{
    if (/$start/i .. /$end/i)
    {
        push @block, $_;
    }

    if (/$end/i)
    {
        for (@block)
        {
            if (/AS \s+ $keyword/ix)
            {
                print join('', @block);
                last;
            }
        }

        @block = ();
    }
}

__DATA__
...