Calling CPI Communications Routines

All CPI Communications calls have a general calling format as follows:

   CALL routine_name        (parameters,return_code)

Some specific calling formats for languages that can invoke the services are:

COBOL

CALL “routine_name” USING parm1,parm2,...return_code

FORTRAN

CALL routine_name (parm1,parm2,...return_code)

C     

routine_name (parm1,parm2,...return_code)

PL/I

CALL routine_name (parm1,parm2,...return_code)

REXX

ADDRESS CPICOMM “routine_name parm1 parm2 ...return_code”

For REXX, enclose the routine name and all parameters within one pair of single or double quotes. Parameters must be initialized to appropriate values. The host command environment resolves the parameter values. For more information, see z/OS TSO/E REXX Reference.

RPG

For RPG, begin the CPI communications call in column 28, and enter the routine name in columns 33-42. For each parameter, list the PARM keyword in column 28 and the parameter value in columns 43-48, as follows:

   C              *OS       CALL "routine_name"
   C                        PARM           parm1
   C                        PARM           parm2...
   C                        PARM           return_code

Any high-level language that conforms to the following linkage conventions may be used to issue CPI Communications calls on MVS:

• Register 1 must contain the address of a parameter list, which is a list of consecutive words, each containing the address of a parameter to be passed. The last word in this list must have a 1 in the high-order (sign) bit.
• Register 13 must contain the address of an 18-word save area.
• Register 14 must contain the return address.
• Register 15 must contain the entry-point address of the service being called.
• If the caller is running in AR ASC mode, access registers 1, 13, 14, and 15 must all be set to zero.