Re: How to properly integrate HLASM SECTALGN with ALIGNT in z/OS binder?
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Peter Relson
Jun 13, 2023, 3:43:50 PM6/13/23
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Jonathan S wrote:
<snip>
By default, alignment stronger than quadword is rounded up to 4K,
for compatibility with the limitations of the load module format.
</snip>
I suspect that, even if this is true, the actual statement is that any alignment stronger than doubleword (rather than quadword) results in the module being loaded on a page boundary. That is a statement for the entire module, not for each individual section. This is simply because the "desired" alignment is not known in the directory entry; there is only a bit for page-aligned vs not page-aligned (which will be doubleword-aligned). So if you need a section ordered on a boundary stronger than doubleword, the module must be on a page boundary.
It is not the case that this necessarily causes the module to be rounded to a 4K multiple.
Peter Relson
z/OS Core Technology Design
<snip>
By default, alignment stronger than quadword is rounded up to 4K,
for compatibility with the limitations of the load module format.
</snip>
I suspect that, even if this is true, the actual statement is that any alignment stronger than doubleword (rather than quadword) results in the module being loaded on a page boundary. That is a statement for the entire module, not for each individual section. This is simply because the "desired" alignment is not known in the directory entry; there is only a bit for page-aligned vs not page-aligned (which will be doubleword-aligned). So if you need a section ordered on a boundary stronger than doubleword, the module must be on a page boundary.
It is not the case that this necessarily causes the module to be rounded to a 4K multiple.
Peter Relson
z/OS Core Technology Design
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