Questions about FDT Load in Compress for IMS COMPRTN

Products

• Compress Data Compression (IMS Tools)

Issue/Introduction

#1
When IMS calls the Compress for IMS (CMPIMS) COMPRTN module, the module loads the related FDT module into IMS region.
How does CMPIMS issue this Load instruction? Does CMPIMS use MVS LOAD SVC, or use IMS's module Load service, or some other way?    

#2
Does CMPIMS issue above Load procedure at each segment record reading / writing?
Also, does the implementation of CMPIMS COMPRTN impose a load on the library due to FDT access?

   

Resolution

Answer to each question as below:

#Q1
When IMS call the CMPIMS COMPRTN module, the module load the related FDT module into IMS region.
How does CMPIMS issue this Load instruction? Does CMPIMS use MVS LOAD SVC, or use IMS's module Load service, or other way?

#A1
We are using the IMS service when running under IMS region.

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#Q2
Does CMPIMS issue above Load procedure at each segment record reading / writing?
Also, does the implementation of CMPIRMS COMPRTN impose a load on the library due to FDT access?

A2
FDT is not loaded during expanding/compressing of every segment. It is kept in memory, which occurs just once during initialization.