Convertible attribute
Because a data set requested by an application program might be
allocated already, dynamic allocation first checks for an existing
allocation that matches the current request. This check avoids redundant
allocation processing. In some cases, an existing allocation matches
the current request except for some parameters. Dynamic allocation
can change certain unmatching parameters of the existing allocation
to meet the current request if the existing allocation has the convertible attribute and the data set is not in
use. The convertible attribute allows dynamic allocation to change
the following parameters of the existing allocation:
- Ddname
- Member name
- Status
- Normal disposition
- Conditional disposition
- Space
- Deallocation at CLOSE
- Input only
- Output only
- DCB attributes
- Password
- Permanently allocated attribute.
The convertible attribute is assigned automatically to all data sets that are dynamically allocated without the permanently allocated attribute. You can, however, assign both the convertible attribute and the permanently allocated attribute to a resource; although you might want to prevent a data set from being automatically deallocated, you might also want to allow some of its parameters to be changed to satisfy a new allocation.