Topic
  • No replies
BillWoodger
BillWoodger
132 Posts

Pinned topic V5.1 Base Locators

‏2013-05-13T16:35:04Z |

I am trying to wait for the documentation...

I was reminded of a comment I saw from Tom Ross about the possible extinction of BLLs (and presumably other Base Locators).

Has this happened? Currently there may be up to 32,000+ "Base Locators" per SECTION, if they remain that would be up to 500,000+, or 1 meg of Base Locators per 2GB. I remember when BLLs used to be loaded individually after the CALL to a program, at least now it is in a loop.

So. Are they there?

  • Tom.Ross
    Tom.Ross
    21 Posts

    Re: V5.1 Base Locators

    ‏2013-05-16T18:16:20Z  

    In most cases you will need only 1 BLL per Linkage Section GROUP, we now use relative addressing instructions, no need for a locator for each 4K of data!  The loop that sets BLLs for large GROUPs passed as parameters is now a thing of the past.

    Tom

  • BillWoodger
    BillWoodger
    132 Posts

    Re: V5.1 Base Locators

    ‏2013-05-16T22:45:26Z  
    • Tom.Ross
    • ‏2013-05-16T18:16:20Z

    In most cases you will need only 1 BLL per Linkage Section GROUP, we now use relative addressing instructions, no need for a locator for each 4K of data!  The loop that sets BLLs for large GROUPs passed as parameters is now a thing of the past.

    Tom

    Thanks Tom, nice to know. I guess the "some cases" (residue after removing "most cases") would be where there are defined data items beyond 4K, rather than an OCCURS which just extends across several/many 4K areas?

  • Tom.Ross
    Tom.Ross
    21 Posts

    Re: V5.1 Base Locators

    ‏2013-05-17T03:30:22Z  

    Thanks Tom, nice to know. I guess the "some cases" (residue after removing "most cases") would be where there are defined data items beyond 4K, rather than an OCCURS which just extends across several/many 4K areas?

    The 'some cases' are cases where data items are larger than can be addressed from one long displacement addressing instruction.  That would be data items larger than 2**20 or 1048576 bytes (rather than the typical limit of 2**12 or 4096 bytes.  We still need to calculate pointers for SS instructions like MVC, but we don't maintain a lot of BLL cells like we used to.

    Tom

    Updated on 2013-05-17T03:32:12Z at 2013-05-17T03:32:12Z by Tom.Ross
  • BillWoodger
    BillWoodger
    132 Posts

    Re: V5.1 Base Locators

    ‏2013-05-17T06:30:37Z  
    • Tom.Ross
    • ‏2013-05-17T03:30:22Z

    The 'some cases' are cases where data items are larger than can be addressed from one long displacement addressing instruction.  That would be data items larger than 2**20 or 1048576 bytes (rather than the typical limit of 2**12 or 4096 bytes.  We still need to calculate pointers for SS instructions like MVC, but we don't maintain a lot of BLL cells like we used to.

    Tom

    Thanks.