Size of config files

[bind at wwwpromote.com]

Hello,

This is probably a non-issue, but I wanted to confirm this before I
implement a sub-domain name system for our users.

We run Bind 8 at this time.  The main configuration file is
/etc/named.conf.  Within this file, we reference files located in a
different directory for each domain that is setup:

zone "domainname.com" {
        type master;
        file "domains/domainname.com";
};

In the domains/domainname.com file, we have a basic record that looks
like this:

;authoritative data for domainname.com
@               IN      SOA     ns.nameserver.com.
hostmaster.ns.nameserver.com.
                                (
                                2003020100      ;Serial Number: YYYYMMDDxx
                                80000           ;Refresh time
                                3600            ;Retry Time
                                604800          ;Time
                                86400           ;Minimum TTL
                                )
                IN      NS      ns.nameserver.com.
                IN      NS      ns2.nameserver.com.
                IN      MX      10      mail
                IN      A       11.222.33.444
www             IN      A       11.222.33.444
ftp             IN      A       11.222.33.444
mail            IN      A       11.222.33.444

My question is, is there any file size limit on this
domains/domainname.com file?

Our plan is to add a new line to the end of the file for each
sub-domain the client sets up:

support         IN      A       11.222.33.444
manual          IN      A       11.222.33.444

I just want to make sure there isn't a limit on this file and I
couldn't find anything that said a for sure yes or no on this.

Thank you in advance for any information!

Best regards,
 David