Let us a say, a GDG is defined with 60 members.
First, a PDS has members. A GDG has generations. Terminology is critical in IT where similar terms may mean very different things. Since no GDG has ever been defined with 60 members, the fast answer to your question is that it cannot be done since GDGs don't have members.
Assuming you actually meant generations
: you will need to design a process to determine how many generations
are required, create the appropriate JCL, and submit it into the internal reader. What you want to do cannot be done without some form of JCL modification and submission into the internal reader.