If your ASCS instance is installed separetly , then it will not show the ENQ process in SM51.
The reason for so is that parameter rdisp/wp_no_enq value is 0 by default in your PAS&AAS instance profiles
And it must be kept that way! 
If you have an ASCS, the enqueue is already there, and the enqueue must be unique at the SAP system. Thus, no instance can have rdisp/wp_no_enq set!