Extract Utility User's Guide - Supra - Cincom

Estimating the size of the stack/heapBecause the size of the stack/heap varies, it is difficult to provide reliableestimates or formulas to determine the size. It is best to use the STACK valueof at least 400K. If this number proves to be insufficient, increase it as neededuntil Extract runs successfully.You know when the size is too small because you receive an error message andan abend code at run-time. The message states that the stack and heap havecollided; that is, they are out of memory.To estimate how much larger to make the stack, consider the level ofcomplexity in the UCL program. Complex tasks require more space. Forexample, if the files from which you extract data have extraordinarily largelogical records, you may discover you need to increase the STACK value.Because the heap area is allocated dynamically, its size varies more than thestack and is harder to predict. The heap gets larger as the UCL gets morecomplex. The size of the heap depends on the number of control blocks Extractcreates for internal use.Extract Utility User's Guide, P25-9513-03 27Chapter: 3. Executing the Extract utilitySection: Choosing run-time options in z/OS