The Applications team have a change that is updating around 61000 elements. The plan is to move all of the elements into Production. Is there a maximum number of element allowed in an Endevor package?
There is no maximum number of elements that can be processed in a package. However, some system resources may be exhausted. You should make use of the DYNAMNBR parm when executing the package, and set it to its maximum value, Plus you should use FREE=CLOSE on all SYSOUT type DD statements if possible.
Another recommendation would be to enable Concurrent Action Processing if your site isn't already utilizing it.