C language application programming

Format

A

B

C

Notes:

• ¹ For AIBTDLI, parmcount is required for C applications.

Parameters

rc

This parameter receives the DL/I status or return code. It is a two-character field shifted into the 2 low-order bytes of an integer variable (int). If the status code is two blanks, 0 is placed in the field. You can test the rc parameter with an if statement. For example, if (rc == 'IX'). You can also use rc in a switch statement. You can choose to ignore the value placed in rc and use the status code returned in the PCB instead.

parmcount

Specifies the name of a fixed binary (31) variable in user-defined storage that contains the number of parameters in the parameter list that follows parmcount.

function

Specifies the name of a character (4) variable, left justified in user-defined storage, that contains the call function to be used. The call function must be left-justified and padded with blanks (such as GUbb)

db pcb

Specifies the name of a pointer variable that contains the address of the database to be used for the call. The PCB address must be one of the PCB addresses passed on entry to the application program in the PCB list.

tp pcb

Specifies the name of a pointer variable that contains the address of the I/O PCB or alternate PCB to be used for the call. The PCB address must be one of the PCB addressed passed on entry to the application program in the PCB list.

aib

Specifies the name of the pointer variable that contains the address of the structure that defines the application interface block (AIB) in user-defined storage.

i/o area

Specifies the name of a pointer variable to a major structure, array, or character string that defines the I/O area in user-defined storage used for the call. The I/O area must be large enough to contain all of the returned data.

i/o area length

Specifies the name of a fixed binary (31) variable in user-defined storage that contains the I/O area length.

area length

Specifies the name of a fixed binary (31) variable in user-defined storage that contains the length of the area immediately following it in the parameter list. Up to seven area lengths or area pairs can be specified.

area

Specifies the name of the pointer variable that contains the address of the structure that defines the user-defined storage to be checkpointed. Up to seven area lengths or area pairs can be specified.

token

Specifies the name of a character (4) variable in user-defined storage that contains a user token.

stat function

Specifies the name of a character (9) variable in user-defined storage that contains the stat function to be performed.

ssa

Specifies the name of a character variable in user-defined storage that contains the SSAs to be used for the call. Up to 15 SSAs can be specified, one of which is rootssa.

rootssa

Specifies the name of a character variable that defines the root segment search argument in user-defined storage.

rsa

Specifies the name of a character variable that contains the record search argument for a GU call or where IMS should return the rsa for an ISRT or GN call.

psb name

Specifies the name of a character (8) variable containing the PSB name to be used for the call.

uibptr

Specifies the name of a pointer variable that contains the address of the structure that defines the user interface block (UIB) that is used in user-defined storage.

sysserve

Specifies the name of a character (8) variable string in user-defined storage to be used for the call.

I/O area

In C, the I/O area can be of any type, including structures or arrays. The ctdli declarations in ims.h do not have any prototype information, so no type checking of the parameters is done. The area may be auto, static, or allocated (with malloc or calloc). You need to give special consideration to C-strings because DL/I does not recognize the C convention of terminating strings with nulls ('\0') Instead of the usual strcpy and strcmp functions, you may want to use memcpy and memcmp.

Example of a DL/I call format

#include <leawi.h>
⋮
CEETDLI (function,db pcb,i/o area,ssa1);

int rc;
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rc=AIBTDLI (parmcount,function,aib,i/o area,ssa1);

#include <ims.h>
int rc;
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rc=CTDLI (function,db pcb,i/o area,ssa1);