Opening files

Opposite are examples of explicitly opening a file or data set for processing.

Remember that an explicit open is not always necessary as EXECIO will perform an automatic implicit open with the first read (DISKR / DISKRU) or write (DISKW) request.

z/OS		z/VM

Open a file for Input (Read) This example opens a file or data set which is going to be read. Open a file for Output (Write) This example opens a file or data set which is going to be written. Open a file for Update (DISKRU + DISKW) This example opens a a file or data set ready for update processing.		The concept of explicit OPEN does not exist in the z/VM implementation.