This section describes restrictions when using GDGs in
MSS:
- The maximum number of host GDG generations that you can reference is 255.
- MSS does not support versioning of the GDG generations, so the only generations that versioning works for are those with a data
set name ending with V00. For example, if the GDG base name is MFIDMF.TEST.GDG then the GDG generation must have the form
MFIDMF.TEST.GDG.G0001V00 ... MFIDMF.TEST.G9999V00, with gaps in the numbering sequence. If you attempt to use a generation
that ends, for example, in V01, it will not be found when GDG names are resolved during program execution.
- A GDG base and all of its generation data sets (GDSs) must reside on the same platform. It is not possible to have a mixture
of GDSs where some reside on the mainframe and others locally.
- If you are using relative generation numbers to reference GDSs in your JCL, for example MFIDMF.TEST.GDG(-4) or MFIDMF.TEST.GDG(+1),
the following restrictions apply:
- If the GDSs are located on a Mainframe Access server, you cannot reference any numbers greater than zero. The only permitted
numbers are 0 through -n, where
n is the maximum number of GDSs supported by the GDG base.
- If the GDSs are located on a PC or network, all processing is supported with only the limitations that are already documented
in this section.
- The GDG ordering options FIFO and LIFO are not supported, either as part of the DEFINE GDG statement or as the GDGORDER parameter
on a DD card.
- GDG generations are returned in LIFO order.