Sharing input

To share SYSIN with a C program, you must compile the application with the STDSYS option and open SYSIN as an input stream file. Avoid using the DD names that are reserved by the C Library.

You can also copy SYSIN to a temporary data set in a prior job step and use that as SYSIN in your PL/I job step; it can be shared when it is not allocated to an instream file.

An input stream file can be opened only once when it is allocated to the SYSIN DD in JCL.

Behavior of the standard C stream for sharing input under MVS batch, TSO batch, IMS batch, and IMS interactive is as follows:

1. stdin goes to DD:SYSIN.
2. If DD:SYSIN does not exist, all read operations from stdin fails.