Data Type


Default Value



This parameter determines whether FMS permits read or write access to files by children threads. The following options are available:

  • 0, Open files once for parent access.
  • 1, Open files once for parent access and again for each child.

If you do not plan to read or write to files from children processes you created by calling FMSPAR, you should leave this parameter at the default value.

For some applications, you may want to populate the matrix by calling FMSPUT, FMSROW or FMSCOL from subroutines you are running in parallel from child threads you created by calls to FMSPAR. In order for FMS to create the file descriptors for concurrent access by children, you must specify the number of children that will have access when the file is opened. This parameter provides that function.

If you are performing raw I/O ( IOTYPE=1) and want access to the raw devices from the children, you must specify this parameter in the license file. Raw devices are opened and initialized during the call to FMSINI.

The number of file descriptors may become large, especially if the file contains a large number of stripes and is accessed by many children. You should reset this value to the default value for all files which do not require access by children.

The valid range of values for IOKIDS is 0, for parent access only, to (MAXCPU - 1) for all children.

On some machines only a single file descriptor is required for access by both the parent and children. In these cases, FMS internally sets the value of IOKIDS to -1 to indicate that the file does not need to be opened also by the children. Any attempt by the application program to change IOKIDS is ignored. While it is not necessary to set IOKIDS on these machines, programming your application as described above will provide portability across all platforms.