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 Strange DDs found in our IDMS cataloged procedure JCL

Michael Cairns's profile image
Michael Cairns posted May 06, 2026 07:44 AM

Dear all,

We have found the following DDNames allocated within our production instance main IDMS system startup JCL.  We do not know where these have come from or what purpose they were ever meant to support, and it is possible they are a relic of some no longer required practice.  They are:

//ALLOC   DD DSN=hlq.SYST.ALLOC,DISP=SHR   
//SECURE  DD DSN=hlq.SECURITY.FILE,DISP=OLD

Our question is, does anyone here recollect using these DDNames within IDMS in the past?  Perhaps a Third Party Product, or some other technique that these might have been put to.  We've checked with Broadcom IDMS Support and they confirm these have never been associated with the product, they suggested we ask here.

Thanks and regards - Mike

PS:  The 'obvious' suggestion that the DISP=OLD was used in some way to enforce serialisation is being considered - so far we don't have a good answer as to 'why' though...