Invoking the ISPF services

Dialog developers use a command or a call statement to invoke ISPF services from functions at the point where the service is needed.

Functions coded in a command procedure language invoke ISPF services by means of the ISPEXEC command. For example:

ISPEXEC DISPLAY PANEL(XYZ)

This example invokes a service to display information on a terminal. A panel definition named XYZ, prepared by the developer and pre-stored in a panel file, specifies both the content and the format of the display.

Functions coded in APL2® invoke ISPF services by using ISPEXEC in an APL2 function. For example:

RC ◄ ISPEXEC 'DISPLAY PANEL(XYZ)'

This example invokes the display service to display information on a terminal by using panel definition XYZ from the ISPF panel file to control the content and format of the display.

Functions coded in a programming language other than FORTRAN, Pascal, or APL2 invoke ISPF services by calling either ISPLINK or ISPEXEC. For example, in PL/I:

CALL ISPLINK ('DISPLAY ', 'XYZ ');

or alternatively, set BUFLEN to 18, then:

CALL ISPEXEC (BUFLEN, 'DISPLAY PANEL(XYZ)');

This example invokes a service to display panel XYZ. FORTRAN and Pascal use only 6 characters, such as ISPLNK or ISPEX, in a called module's name.

Thus, the FORTRAN or Pascal call is in this format:

lastrc = ISPLNK ('DISPLAY ', 'XYZ ')

or alternatively:

lastrc = ISPEX  (18, 'DISPLAY PANEL(XYZ)')

ISPLINK and ISPEXEC can be called from programs coded in any language that uses standard OS register conventions for call interfaces and the standard convention for signaling the end of a variable-length parameter list. Assembler programs must include code to implement the standard save area convention.