Are the sample Numbered exits EXIT 17(X17STUB) and EXIT 18 (X18STUB) still valid at IDMS release 18.5 and higher?

Document ID : KB000029527
Last Modified Date : 14/02/2018
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Question:

At IDMS 18.5, after installing IDMS, I no longer see EXIT 17 and EXIT 18 entries in module RHDCUXIT. What changed since IDMS r18.0?

The IDMS r18.0 RHDCUXIT contained the following #DEFXIT entries:

* RHDCUXIT                                                        

         #DEFXIT MODE=SYSTEM,CALL=DC,EP=X17STUB                   

         #DEFXIT MODE=SYSTEM,CALL=DC,EP=X18STUB                   

Answer:

X17STUB and X18STUB were example exits. Exits 17 & 18 are used to examine and/or manipulate data streams. Exit17 is invoked for input data stream, before they are turned over to programs; Exit18 is invoked for output data streams, before they are displayed on terminals.

 

For 18.5, we've removed them from RHDCUXIT as it seems clients reported Performance problems with zIIP processing due to swapping from TCB to SRB and back when these two exits were called. Thus EXIT 17 and EXIT 18 were removed as defaults in RHDCUXIT for 18.5. See Problem IDMS/4511:

PROBLEM DESCRIPTION:

RHDCUXIT default implementation of exit 17  & 18 is removed via source update in release 18.5.

Exit 17 & 18 are no longer implemented as the default in module RHDCUXIT.

If client needs to implement EXIT 17 and EXIT 18 input and output datastream exits, they must implement them via the #DEFXIT that is contained in the RHDCUXIT sample.

The reason for the change is that zIIP processing in a CV was doing TCB SRB  change modes excessively at sites because exit 17 and 18 were defined in  the RHDCUXIT unnecessarily.

This change should only affect DBCS, FACOM, HITACHI or CASDATA clients using those product exits.

For IDMS r19.0; when DBCS is selected for install; (EJJ000OP = YES CA IDMS DBCS in the VARBLIST); it generates this incorrect text in JOB03. However, the 19.0 RHDCUXIT source macro, as these two commented out. 

//*** CUSTOMIZED ASSEMBLIES AND LINKS *** 
//*** *** 
//*** Before running this job, modify the RHDCUXIT *** 
//*** source to include these two lines for DBCS: *** 
//*** *** 
//*** #DEFXIT MODE=SYSTEM,CALL=DC,EP=X17STUB INPUT *** 
//*** #DEFXIT MODE=SYSTEM,CALL=DC,EP=X18STUB OUTPUT *** 
//*** *** 
//*** See the 19.0 Release Notes for more information. *** 
//*** *** 

This text is incorrect and has been correct in Problem IDMS 5180 and PTF TR87728:

JOB03 INCORRECT RHDCUXIT INFORMATION FOR DBCS USERS                   

PROBLEM DESCRIPTION:                                                 

Job03 of the Caisag install incorrectly states that that DBCS        

users need to include exits 17 and 18 in their RHDCUXIT.             

SYMPTOMS:                                                            

Job03 incorrectly tells DBCS users to include Exit 17 and 18          

and their RHDCUXIT.                                                  

IMPACT:                                                              

DBCS users may include unnecessary exits.                            

CIRCUMVENTION:                                                       

Do not include Exit 17 and 18.