DISP OLD denotes exclusive control of the dataset;

DISP MOD is used when the dataset can be extended ie you can add records at the end of an existing dataset.

disp old refers to dataset already created.

disp new refers to dataset to be created at end of this step

disp mod refers some data contents are added at end of dataset if

dataset already present or a new dataset is created if it is not already present.

one more important thing that in extend mode of file both disp old and disp mod will add the data at end

while in i-o mode disp old overwrites on previous record while

disp mod appends........

but I have seen in several cases that DISP SHR is also used as a out file( but DCB was not given there) how I can be modified or newly created?? please reply

Thanks

Amit

Coding the status filed as OLD results in the OS searching for an existing data set of the name specified. If the file is written to then its old data will be lost replaced by the new data

Setting DISP as SHR is identical to OLD except when OLD gives exclusive control of the dataset to the user whereas SHR allows multiple jobs to read the same dataset