ASA 5510 as DHCP Server

We have a remote office that has downsized significantly and will be moving its few remaining people into a shared office space.  They are not going to have any servers in this new location and a shared Internet connection (shared with other tenants) in the beginning but we will have our own dedicated Internet line eventually.  Currently they have a Cisco 1841 as their gateway router and an ASA 5510 for their firewall, use Windows servers for DHCP, and DNS, and are joined to our corporate domain (DOMAIN.LOCAL).  

Next week we are shutting down all of their servers and shipping them to other locations so they won't be able to get DHCP but they need to keep working in their current building for a few weeks.  I want to enable DHCP on the ASA but have a question.

I'm going to do the statement:  dhcpd address 192.168.16.101-192.168.1.151 inside

How do I specify the subnet they are given.  Currently that site runs on a /21 so they need to keep that for all the routes to work and to be able to communicate with the network equipment.  Will the ASA give the /21 subnet by default since that is what is is configured with?