APSB call

The Allocate PSB (APSB) call is used to allocate a PSB for a CPI Communications driven application program. These types of application programs are used for conversations that include LU 6.2 devices.

Format

Read syntax diagramSkip visual syntax diagramAPSBaib
Call Name DB/DC DBCTL DCCTL DB Batch TM Batch
APSB X   X    

Parameters

aib
Specifies the application interface block (AIB) that is used for the call. This parameter is an input and output parameter.
The following fields must be initialized in the AIB:
AIBID
Eye catcher. This 8-byte field must contain DFSAIBbb.
AIBLEN
AIB lengths. This field must contain the actual length of the AIB that the application program obtained.
AIBRSNM1
Resource name. This 8-byte, left-justified field must contain the PSB name.

Usage

CPI-C driven application programs must be link edited with the IMS language interface module and must indicate the PSB to be used before the application program can issue DL/I calls. The APSB call uses the AIB to allocate a PSB for these types of application programs.

When you issue the APSB call, IMS TM returns a list of PCB addresses contained in the specified PSB to the application program. The PCB list is returned in the AIBRSA1 field in the AIB.

IMS TM allows the APSB call to complete even if the databases that the PSB points to are not available. You can issue the INIT call to inform IMS TM of the application program's capabilities to accept additional status codes regarding data availability.

Related reading: For more information on CPI Communications driven application programs, see IMS Version 15.2 Communications and Connections.

Restrictions

An application program that uses APSB can allocate only one PSB at a time. If your application requires more than one PSB, you must first release the PSB in use by issuing the deallocate PSB (DPSB) call.

CPI Communications driven application programs must issue the APSB call before issuing any other DL/I calls. If your application program attempts to issue DL/I calls before a PSB has been allocated with the APSB call, the application program receives error return and reason codes in the AIB.