DALUNQDS indicates that a temporary data set is being allocated and that the address space allocating the data set will only allocate the specified data set name, or generated data set name, to the DD currently being allocated, and no other DD.
Dynamic allocation normally tracks temporary data set names when they are allocated and uses this information to avoid deleting a temporary data set more than once when the data set is allocated multiple times. Use of this text unit indicates that the dynamic allocation caller will ensure that the temporary data set is only allocated once and that the system can avoid this processing.
When you code DALUNQDS, # must be zero. LEN and PARM are not specified.
KEY # LEN PARM
0077 0000 - -