UCB size in MVS

[Cristina y Enrique]

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Hi team,

Who knows which is the size of an UCB?. I mean, each dasd volume has an Unit Control Block (UCB) in memory, i need to calculate how much memory will be used by 256 3390-3 volumes.
Thanks in advance,
Enrique.

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[PeterH5322-2]

On Aug 19, 2009, at 1:20 PM, cdeleon@... wrote:

> Who knows which is the size of an UCB?. I mean, each dasd volume  
> has an Unit Control Block (UCB) in memory, i need to calculate how  
> much memory will be used by 256 3390-3 volumes.

A UCB has a foundation portion, an extension portion and a prefix  
portion.

A device type of DUMMY gives you a UCB which can accept a later, real  
device type, except for DASD, which is one reason why HASP and other  
systems used DUMMY device types for all their UR and tape devices.  
Probably their CTC devices as well (although CTC requires an  
attention handler, which few other devices, except graphics devices,  
require).

Of course, the above does not answer your question directly, but it  
should indicate that the UCB size "depends". Depends upon paths,  
features, and other items of interest to IOS (IECIOSCN, in MVS).

[somitcw-2]

   Assuming MVS 3.8j, I used:
look24
ltold
ltio
then picked a disk UCB address and found:

1848 00C8FF8E 01480000 70000100 00F1F4F8 *.H...........148*
1858 3070200B 00006420 00010100 D4E5E2D9 *............MVSR*
1868 C5E21005 00000600 00000000 00FF7810 *ES..............*
1878 0088FF84 01490000 70000100 00F1F4F9 *.............149*
1888 3070200B 00006438 00010100 E2D4D7F0 *............SMP0*
1898 F0F10800 00000000 00000000 00FF7810 *01..............*
18A8 0088FF84 014A0000 70000100 00F1F4C1 *.............14A*
18B8 3070200B 00006450 00010100 E2D4D7F0 *............SMP0*
18C8 F0F20800 00000000 00000000 00FF7810 *02..............*
18D8 0088FF84 014B0000 70000100 00F1F4C2 *.............14B*
18E8 3070200B 00006468 00010100 E2D4D7F0 *............SMP0*
18F8 F0F30800 00000000 00000000 00FF7810 *03..............*
1908 0088FF84 014C0000 70000100 00F1F4C3 *.............14C*
1918 3070200B 00006480 00010100 E2D4D7F0 *............SMP0*
1928 F0F40800 00000000 00000000 00FF7810 *04..............*

   It appears that each is 48 bytes ( X'30' ).

   The extension appears to be 24 bytes ( X'18' ).

   I could be reading wrong.  Please check my numbers.

[somitcw-2]

--- In H390-MVS@...,
 "somitcw" <somitcw@...> wrote:

>    Assuming MVS 3.8j, I used:
> look24
> ltold
> ltio
> then picked a disk UCB address and found:
> 1848 00C8FF8E 01480000 70000100 00F1F4F8 *.H...........148*
> 1858 3070200B 00006420 00010100 D4E5E2D9 *............MVSR*
> 1868 C5E21005 00000600 00000000 00FF7810 *ES..............*
> 1878 0088FF84 01490000 70000100 00F1F4F9 *.............149*
> 1888 3070200B 00006438 00010100 E2D4D7F0 *............SMP0*
> 1898 F0F10800 00000000 00000000 00FF7810 *01..............*
> 18A8 0088FF84 014A0000 70000100 00F1F4C1 *.............14A*
> 18B8 3070200B 00006450 00010100 E2D4D7F0 *............SMP0*
> 18C8 F0F20800 00000000 00000000 00FF7810 *02..............*
> 18D8 0088FF84 014B0000 70000100 00F1F4C2 *.............14B*
> 18E8 3070200B 00006468 00010100 E2D4D7F0 *............SMP0*
> 18F8 F0F30800 00000000 00000000 00FF7810 *03..............*
> 1908 0088FF84 014C0000 70000100 00F1F4C3 *.............14C*
> 1918 3070200B 00006480 00010100 E2D4D7F0 *............SMP0*
> 1928 F0F40800 00000000 00000000 00FF7810 *04..............*
> It appears that each is 48 bytes ( X'30' ).
> The extension appears to be 24 bytes ( X'18' ).
> I could be reading wrong.  Please check my numbers.

  72 bytes times 256 = 18432 ( X'4800' )

[Cristina y Enrique]

Thanks a lot for the information.

See you.
  ----- Original Message -----
  From: somitcw
  To: H390-MVS@...
  Sent: Wednesday, August 19, 2009 4:31 PM
  Subject: [H390-MVS] Re: UCB size in MVS


    --- In H390-MVS@...,
  "somitcw" <somitcw@...> wrote:
  > Assuming MVS 3.8j, I used:
  > look24
  > ltold
  > ltio
  > then picked a disk UCB address and found:
  > 1848 00C8FF8E 01480000 70000100 00F1F4F8 *.H...........148*
  > 1858 3070200B 00006420 00010100 D4E5E2D9 *............MVSR*
  > 1868 C5E21005 00000600 00000000 00FF7810 *ES..............*
  > 1878 0088FF84 01490000 70000100 00F1F4F9 *.............149*
  > 1888 3070200B 00006438 00010100 E2D4D7F0 *............SMP0*
  > 1898 F0F10800 00000000 00000000 00FF7810 *01..............*
  > 18A8 0088FF84 014A0000 70000100 00F1F4C1 *.............14A*
  > 18B8 3070200B 00006450 00010100 E2D4D7F0 *............SMP0*
  > 18C8 F0F20800 00000000 00000000 00FF7810 *02..............*
  > 18D8 0088FF84 014B0000 70000100 00F1F4C2 *.............14B*
  > 18E8 3070200B 00006468 00010100 E2D4D7F0 *............SMP0*
  > 18F8 F0F30800 00000000 00000000 00FF7810 *03..............*
  > 1908 0088FF84 014C0000 70000100 00F1F4C3 *.............14C*
  > 1918 3070200B 00006480 00010100 E2D4D7F0 *............SMP0*
  > 1928 F0F40800 00000000 00000000 00FF7810 *04..............*
  > It appears that each is 48 bytes ( X'30' ).
  > The extension appears to be 24 bytes ( X'18' ).
  > I could be reading wrong. Please check my numbers.

  72 bytes times 256 = 18432 ( X'4800' )