Programs in 31-bit addressing mode sometimes need to use 24-bit
addressing mode programs to perform an I/O operation.
A 31-bit addressing mode program can perform an I/O operation by:
- Using VSAM, QSAM, BSAM, BPAM and BDAM services that accept callers
in either 24-bit or 31-bit addressing mode. (z/OS DFSMS Using Data Sets describes
these services and shows examples. The functions that require 24-bit
mode are ISAM, some BDAM functions and BSAM and QSAM with a TSO terminal
or IBM® 3886 or 3890 Document
Processor.)
- Using the EXCP macro. All parameter lists, control blocks, CCWs,
virtual IDAWs, and EXCP appendage routines must reside in virtual
storage below 16 megabytes. See Using the EXCP macro for a description
of using EXCP to perform I/O. CCWs can reside above the 16 MB line
and virtual IDAWs can point above the 16 MB line or above the 2 GB
bar.
- Using the EXCPVR macro. All parameter lists, control blocks,
CCWs, IDALs (indirect data address lists), and appendage routines
must reside in virtual storage below 16 megabytes. See Using EXCPVR for a description of using EXCPVR to perform I/O.
CCWs can reside above the 16 MB line and virtual and real IDAWs can
point above the 16 MB line or above the 2 GB bar.
- Invoking a routine that executes in 24-bit addressing mode as
an interface to the 24-bit access methods, which accept callers executing
in 24-bit addressing mode only. See Establishing linkage for more
information about this method.
- Using the method shown in Figure 1.