*LDA Local data area data structure in RPG AS400

*LDA Local data area data structure in RPG AS400

What is *LDA Local Data Area for IBM i

A local data area is created for each Job in the IBM i system which is initially blank with a length of 1024 and type *CHAR.

We can refer to the Job's local data area by specifying *LDA for the DTAARA keyword on DSPDTAARA, CHGDTAARA, and RTVDTAARA command.

The local data area is unique and specific to the job. Therefore we cannot refer one job *LDA from other jobs.

No library is associated with the *LDA local data area.

We cannot Create, Delete or Allocate an *LDA local data area.

We can use the *LDA local data area to pass information to a procedure or program without using the parameters.

We can use *LDA local data area to store information without the need to create or delete the data area by ourselves.

Submit Job (SBMJOB) command allows us to pass the data of the submitting job's local data area to the new job.

Run the below command to see the *LDA of your job.

dspdtaara *LDA

                               Display Data Area                      
                                                             System:  
 Data area . . . . . . . :   *LDA                                     
 Type  . . . . . . . . . :   *CHAR                                    
 Length  . . . . . . . . :   1024                                     
 Text  . . . . . . . . . :   *LDA for Job 003990/EASYCLASS/QPAD191838 
                                                                      
                                                                      
            Value                                                     
 Offset      *...+....1....+....2....+....3....+....4....+....5       
     0      '                                                  '      
    50      '                                                  '      
   100      '                                                  '      
   150      '                                                  '      
   200      '                                                  '      
   250      '                                                  '      
   300      '                                                  '      
   350      '                                                  '      
   400      '                                                  '      

What is *LDA Local data area data structure?

When we do not specify the name of the data structure and use UDS and do not specify the DTAARA keyword then it's a data area data structure.

Specify DTAARA(*LDA) then it's a data area data structure.

Use *N (No name) and DTAARA(*AUTO) to refer to *LDA local data area data structure.

No need to perform read (IN) and write (OUT) to *LDA local data area data structure. At program initialization, *LDA contents are being read, and at program termination, the local data area contents get updated.

Declaring *LDA local data area data structure in Fixed format RPG

     D                UDS                          
     D subfld1                       10a                      

Or

     D ldaDS          UDS                  DTAARA(*LDA)  
     D subfld1                       10a                           

Declaring *LDA local data area data structure in Fully Free-format RPG

dcl-ds *n dtaara(*auto) ;
  subfld1 char(10);
end-ds;

Or

dcl-ds ldaDS dtaara(*LDA) ;
  subfld1 char(10);
end-ds;                     

Coding *LDA local data area data structure in RPGLE Fixed, /Free and Fully Free format.

In this example, we write data to *LDA local data area data structure.

RPG Code in Fixed format for *LDA Local Data Area data structure in RPGLE AS400

      * unnanmed data area ds                                                             
      * don't require IN/OUT for *lda ds (INIT --> IN and TERM --> OUT)                  
      * created for each job. (1024 char (blank))                                        
      * dspdtaara *lda (cannot create, delete,allocate, no library associated with this)                                
     D                UDS                                         
     D subfld1                       10a         
      * You can define *LDA as below too. Currently below definition commented.                 
     D*ldaDS          UDS                  DTAARA(*LDA)           
     D*subfld1                       10a                                                                                     
     C                   EVAL      sbfld1 = 'hello lda'                                            
     C                   SETON                                            LR 
     C                   RETURN                                                                                     

RPG Code in /Free format for *LDA Local Data Area data structure in RPGLE AS400

     D                UDS                                                               
     D subfld1                       10a   
      * You can define *LDA as below too. Currently below definition commented.                                                    
     D*ldaDS          UDS                  DTAARA(*LDA)                                 
     D*subfld1                       10a                                                
      /Free                                                                                                                                            
          subfld1 = 'hello lda';                                                        
          *inlr = *on;                                                                  
          return;                                                                       
      /End-Free                                                                                                                                                                                                                                                

RPG Code in Fully Free format for *LDA Local Data Area data structure in RPGLE AS400

**FREE                            
dcl-ds *N DTAARA(*AUTO);          
 subfld1 char(10);                
end-ds;                           
          subfld1 = 'hello lda';  
          *inlr = *on;            
          return;                                                               

RPG Code in Fully Free format for *LDA Local Data Area data structure in RPGLE AS400

**FREE                            
dcl-ds ldaDS DTAARA(*LDA);        
 subfld1 char(10);                
end-ds;                           
   IN ldaDS;                      
          subfld1 = 'hello lda';  
   OUT ldaDS;                     
          *inlr = *on;            
          return;                                                                              

Output

                               Display Data Area                      
                                                             System:  
 Data area . . . . . . . :   *LDA                                     
 Type  . . . . . . . . . :   *CHAR                                    
 Length  . . . . . . . . :   1024                                     
 Text  . . . . . . . . . :   *LDA for Job 003990/EASYCLASS/QPAD191838 
                                                                      
                                                                      
            Value                                                     
 Offset      *...+....1....+....2....+....3....+....4....+....5       
     0      'hello lda                                         '      
    50      '                                                  '      
   100      '                                                  '      
   150      '                                                  '      
   200      '                                                  '      
   250      '                                                  '      
   300      '                                                  '      
   350      '                                                  '      
   400      '                                                  '      
                                                                      
 Press Enter to continue.                                             

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