Cisco Systems and the ASA Services Module Manual De Usuario

If you enable standard priority queuing for traffic on a physical interface, then you need to also create 
the priority queue on each interface. Each physical interface uses two queues: one for priority traffic, 
and the other for all other traffic. For the other traffic, you can optionally configure policing.

The standard priority queue is not required for hierarchical priority queuing with traffic shaping; see the 

 for more information.

(ASASM) The ASASM does not support priority queuing.

(ASA 5580) You cannot create a standard priority queue for a Ten Gigabit Ethernet interface. Note: 
For the ASA 5585-X, standard priority queuing is supported on a Ten Gigabit Interface.

(ASA 5512-X through ASA 5555-X) Priority queuing is not supported on the Management 0/0 
interface.

2.

Typically, the maximum size is 1538 bytes, or 1542 bytes for tagged Ethernet. If you allow jumbo frames (if supported for your 
platform), then the packet size might be larger.

3.

The delay depends on your application. For example, to control jitter for VoIP, you should use 20 ms.

 interface_name

ciscoasa(config)# priority-queue inside

Creatse the priority queue, where the interface_name argument 
specifies the physical interface name on which you want to enable 
the priority queue, or for the ASA 5505 or ASASM, the VLAN 
interface name.