If the specified resource is associated with a permanently concatenated group, described in Requesting the permanently concatenated attribute, the in-use attribute is removed from all members of the group, and the count of the number of resources held for reuse is increased by the number of members in the group. (See In-use attribute for a description of the in-use attribute.)
An exception occurs when the concatenated group was generated by the system, such as generation data groups that are GDG ALL groups. In these cases, the group is treated as a single resource.
If a concatenated group has the permanently concatenated attribute and you specify a ddname with a dsname, or GDG ALL, the entire group is released. If you specify a dsname with GDG ALL, the request for dynamic unallocation fails. (See Deallocating resources by ddname for considerations when deallocating resources by ddname.)
GDGs are described in z/OS MVS JCL User's Guide.
If the concatenated group does not have the permanently concatenated attribute, the group is deconcatenated and the member associated with the specified dsname is released. (The first member is released if the group's ddname is specified.)