The AUXPROC Option of the FILEDEF Command
The AUXPROC option can only be used by a program call to FILEDEF and not
from the terminal. The CMS language interface programs use this feature for spe­
cial I/O handling of certain (utility) data sets.
The AUXPROC option, followed by a fullword address of an auxiliary processing
routine, allows that routine to receive control from DMSSEB before any device I/O is performed. At the completion of its processing, the auxiliary routine returns
control to DMSSEB signaling whether or not I/O has been performed. If it has not
been done, DMSSEB performs the appropriate device I/O. When control is received from DMSSEB, the general-purpose registers contain the
following information: GPR2 = Data Control Block (DCB) address GPR3 = Base register for DMSSEB GPR8 = CMS OPSECT address GPR11 = File Control Block (FCB) address GPR14 = Return address in DMSSEB GPR15 = Auxiliary processing routine address
all other registers = Work registers
The auxiliary processing routine must provide a save area in which to save the gen­
eral registers; this routine must also perform the save operation. DNISSEB does
not provide the address of a save area in general register 13, as is usually the case.
When control returns to DMSSEB, the general registers must be restored to their
original values. Control is returned to DMSSEB by branching to the address con­
tained in general register 14. GPR15 is used by the auxiliary processing routine to inform to DMSSEB of the
action that has been or should be taken with the data block as follows:
Register
Content Action GPR15=O No I/O performed by AUXPROC routine; DMSSEB will perform I/O. GPR15<O I/O performed by AUXPROC routine and error was encountered.
DMSSEB will take error action. GPR15>O I/O performed by AUXPROC routine with residual count in GPR15; DMSSEB returns normally.
GPR15=64K I/O performed by AUXPROC routine with zero residual count. OS Macro Simulation Under eMS 385

VSE Support Under eMS CMS supports interactive program development for VSE. This includes creating,
compiling, testing, debugging, and executing commercial application programs.
The VSE programs can be executed in a CMS virtual machine or in a CMS Batch
Facility virtual machine. VSE files and libraries can be read under CMS. VSAM data sets can be read and
written under CMS. The CMS/DOS environment (called CMS/DOS) provides many of the same facili­
ties that are available in VSE. However, CMS/DOS supports only those facilities
that are supported by a single (background) partition. The VSE facilities supported
by CMS/DOS are: VSE linkage editor
Fetch support VSE Supervisor and I/O macros VSE Supervisor control block support
Transient area support VSE/VSAM macros
This environment is entered each time the CMS SET DOS ON command is issued; VSAM functions are available in CMS/DOS only if the SET DOS ON (VSAM) command is issued. In the CMS/DOS environment, CMS supports many VSE facilities, but does not support OS simulation. When you no longer need VSE sup­
port under CMS, you issue the SET DOS OFF command and VSE facilities are no
longer available. CMS/DOS can execute programs that use the sequential access method (SAM) and virtual storage access method (VSAM), and can access VSE libraries. CMS/DOS cannot execute programs that have execution-time restrictions, such as
programs that use teleprocessing access methods or multitasking. DOS/VS COBOL, DOS PL/I, DOS/VS RPG II, and Assembler language programs are exe­
cutable under CMS/DOS. All of the CP and CMS online debugging and testing facilities (such as the CP ADSTOP and STORE commands and the CMS DEBUG environment) are sup­
ported in the CMS/DOS environment. Also, CP disk error recording and recovery
is supported in CMS/DOS. With its support of a CMS/DOS environment, CMS becomes an important tool for VSE application program development. Because CMS/DOS is designed as a VSE program development tool, it assumes in many cases that a VSE system exists, and
uses it. The following sections describe what is supported, and what is not.
386 VM/SP System Programmer's Guide