FWIW I use HEAPCHK as part of the standard regression testing of a product
written in C++. I don't notice the performance impact while the product is
running (but that is a very subjective "don't notice" -- I have made no
attempt to measure the impact because I don't really care about the
performance of one test). I use RPTSTG(ON) as part of the same test and one
of them really slows down termination: a product termination that normally
is essentially instantaneous takes perhaps 30 seconds. I do a lot of
delete's at that point so perhaps it is HEAPCHK that slows things down.
//CEEOPTS DD *
RPTSTG(ON)
HEAPCHK(ON,1,0,10,10,1024,0)
/*
HEAPZONE sounds useful. A similar feature is the default in MS Visual Studio
(where I do my alpha testing -- and I suspect similarly in things like
Eclipse). It works great. If you allocate 27 bytes and use 28, then on the
free() or delete C++ asserts. You tend to find buffer overruns shortly after
they happen, rather than down the road when all sorts of seemingly unrelated
things start misbehaving.
Charles
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On
Behalf Of Lizette Koehler
Sent: Monday, December 02, 2013 6:15 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: HEAPCHECK and HEAPZONE difference in zOS 2.1
Miklos,
I found HEAPCHK in z/OS Language Environment Customization
HEAPCHK Derivation: HEAP storage CHecKing Use HEAPCHK to run additional
heap check tests.
If HEAPCHK(ON) is used with STORAGE(,heap_free_value), the free areas of the
heap will also be checked.
If HEAPCHK(ON) is specified, this will result in a performance degradation
due to the additional error checking that is performed.
A U4042 abend dump will be generated when an error is detected, but no
CEEDUMP will be produced.
And for HEAPZONE I found in z/OS Language Environment Programming Reference
Derivation: HEAP check ZONES
The HEAPZONES runtime option is used to turn on overlay toleration and
checking for user heaps. When activated, the runtime option affects any
obtained storage that can be controlled by the HEAP or HEAP64 runtime
options. HEAPZONES also affects storage obtained from a heap pool. A heap
check zone is an additional piece of storage that is appended to an
allocated element during a storage request. The size of the check zone
depends on the size31 and size64 suboptions of HEAPZONES. The check zone can
be examined for overlays when the heap element is freed.
So it looks that HEAPCHK has a performance overhead and validates heaps of
(I think) all HEAPS and the other a runtime option to provide overly
toleration and check for USER heaps.
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