TPXL0037 NO ACB AVAILABLE condition

Products

• TPX - Session Management

Issue/Introduction

"TPXL0037 NO ACB AVAILABLE FOR userid applid" is issued when no eligible virtual terminal (VT) is available to start a session.
If no user ID is available, the message shows the real terminal name. This document discusses possible causes for this.

Environment

Release: 5.4
Component: YPX for Z/Os

Resolution

A few possible causes for this issue are:

1) If using dynamic logmodes:

• When a terminal logs on to TPX, it is assigned a TPX logmode to be used for application session requests.
  
  
• Prior to 5.3, that logmode would be something like T3278Mnx

• "n" is the model number (2,3, etc.), and
• "x" will either be an "E" or blank depending on the query capabilities of the terminal.

• Release 5.3 goes through the same process unless the terminal's PSERVIC indicates a dynamic logmode.
  In that case, the application session logmode will be set to T3278MDE for that terminal.

• TPX will then run through the virtual terminal list looking for an "nx" value that matches the "nx" value already
  assigned to the real terminal for establishing an application session. If none is found, you get TPXL0037.
  
  
• With TPX 5.3, since the "nx" value for a dynamic logmode terminal is "DE", unless you have implemented the 5.3 logmode tables
  that include T3278MDE (or updated your customized tables with an entry for T3278MDE) this will not match any of the
  virtual terminal logmodes. That results in the "NO ACB AVAILABLE" situation occurring.
  
  

NOTE: It is possible to disable the TPX dynamic logmode code with SMRT Optional Parameter option #38
           (fPTF's RO21026 & RO21027 required) so that logmodes are determined the same way as prior to TPX 5.3.

2) Application definition:

• When the ACT entry for an application has "Model sensitive" and/or "Extended datastream" set to "Y",
  TPX will look for the particular model number in the "n" location stated above and/or the presence or absence
  of the "E" in the "x" location.
  Unless these specific logmodes are defined within your assembled logmode table, you will get TPXL0037.
  
  
• If you are running out of a specific type of VT, such as UNQ, it may be possible that the application could be defined with type GRP or SHR.

Otherwise:

• Do you validly need to add more VTs? For example, if you have added more users to an application defined with type UNQ, you may need to increase your capacity.

 
3) You likely have restrictions in the selection of the virtual terminal for this application.

There are three places where you can check that:

3.1. Restriction by application 
Go to TPXADMIN, select "2 – TPX System Options" and "2 - Application Definition".
Then select the ACT in use and the applid. Please check field 'Mask entry name'.
If there is an entry, the selection of virtual terminals is restricted by the Mask specified.
That mask is defined in the Masking Rules (in TPXADMIN, options '2 TPX System Options' and then '3  Virtual Terminal Masking Rules').
The user is unable to logon if the rule is too restrictive or provides too less terminal names. 

3.2. Restriction by user 
Go to TPXADMIN, select '1  TPX User/Group Maintenance' and '3 - User Maintenance' and enter the users name.
Then select '1 - TPX User Options' and scroll forward with PF8 once.
You are now in panel TEN0125 titled 'TPX Userid Maintenance Detail Panel'. 
Check if field 'ACB mask default:' is populated. If so, this is the mask's name which is defined in the Masking Rules. 

3.3. Restriction by user for that application 
Go to TPXADMIN, select '1  TPX User/Group Maintenance' and '3 - User Maintenance' and enter the users name.
Then select '2 - TPX Session Options' and select the session <applid>.
Check if field 'ACB Mask' is populated. If so, this is the mask's name which is defined in the Masking Rules.

Options are:
- Define more virtual terminals for the given Masking Rule
- Remove the rule (if applicable)
- Use a less restrictive rule (if applicable)

3.4. No Rules at all
If no rules are in place, check if there are enough virtual terminals of Type UNQ or GRP available and define more if necessary.