When opening a file, Endevor needs to ensure that the file it has opened cannot be opened simultaneously by LSERV.
This QNAME will primarily be issued by L-Serv code to assume Exclusive control over a Dataset.
It will both make sure that any L-Serv instance can't take control (by command ADDFILE) of these datasets, and it signals to LServ's ´clients´ like Endevor that L-Serv controls the dataset.
Endevor , before it OPEN's a dataset, will check whether it is under LSERV control, via an ENQ Test with Qname LSERVDSN and as Rname the dataset name.
If it is NOT under LSERV control, Endevor will next issue a Shared ENQ SCOPE=SYSTEMS, with Qname LSERVDSN, as Rname the dataset name and this will persist until Endevor closes the dataset.
Thus it makes sure that L-SERV can't take Exclusive control over the dataset.
For example, this is relevant in a configuration where both L-Serv and RLS are potentially used.