Rexx Command Environment Support; Adding Rexx Host Command Environments; Support Of Standard Cics Features/Facilities; Cics Mapped I/O Support - IBM SC34-5764-01 Manual

REXX General Concepts
v The USERID function returns a 1 to 8 character CICS user ID if the user is signed on. If the CICS user
has not signed on and a default user has been specified for the CICS region (by the CICS Systems
Programmer specifying DFLTUSER in the CICS startup parameters) then that value is used.
Note: The default user shares REXX File System and REXX List System directories.
v The STORAGE function, that allows a REXX user to display or modify the virtual storage of the CICS
region. This function can only be successfully invoked from an authorized exec or by an authorized
user.

REXX Command Environment Support

REXX command environments that are currently available (to use with the REXX ADDRESS command)
are REXXCICS, CICS, EXECSQL, EDITSVR, FLSTSVR, RFS and RLS.

Adding REXX Host Command Environments

Support is provided for allowing new REXX/CICS commands and command environments to be
dynamically defined. New commands may be written in REXX or in any REXX/CICS supported language
(for example: Assembler, COBOL, C, PL/I). For more information on how commands and command
environments are defined to REXX/CICS, see Chapter 21, "REXX/CICS Command Definition," on page
281.

Support of Standard CICS Features/Facilities

This section discusses the support of standard CICS features/facilities such as: CICS mapped I/O support,
dataset I/O services, interfaces to CICS facilities and services, issuing user applications from execs, REXX
interfaces to CICS temporary and transient storage queues, pseudo-conversational transaction support,
and DBCS support.

CICS Mapped I/O Support

Support for CICS basic mapping support (BMS) I/O is provided by the CICS SEND MAP, RECEIVE MAP,
and CONVERSE MAP commands and the REXX/CICS CONVTMAP and COPYS2R commands. See
Appendix J, "Basic Mapping Support Example," on page 427.
Note: BMS maps must be predefined, using normal CICS procedures.

Dataset I/O Services

Standard CICS File I/O commands (EXEC CICS READ, WRITE, and so on) are supported. Also,
high-level I/O may be done from an exec to the VSAM-based REXX File System (RFS) using the provided
RFS command. In addition, standard VSE Librarian members may be used with the IMPORT and
EXPORT commands and the REXX/CICS editor.

Interfaces to CICS Facilities and Services

From within the ADDRESS CICS command environment, support is provided for most CICS commands
(as defined in the CICS Transaction Server for VSE/ESA Application Programming Reference. See
Chapter 25, "REXX/CICS Commands," on page 319 for detailed information on the commands supported.

Issuing User Applications From Execs

REXX/CICS supports the EXEC CICS START, LINK, and XCTL commands to provide the ability to START
CICS transactions or invoke CICS programs from within a REXX exec.

REXX Interfaces to CICS Storage Queues

Command support exists for reading, writing, and deleting CICS temporary storage and transient data
queues from REXX/CICS.
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