VMS Help RUN, Process, Qualifiers, /SUBPROCESS_LIMIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SUBPROCESS_LIMIT=quota

    Specifies the maximum number of subprocesses that the created
    process is allowed to create.

    The default quota is the quota established at system generation
    time. A process does not require any subprocess quota in order to
    execute.

    The subprocess limit quota is pooled.