COMM macro statement

The APPLID parameter defines the VTAM® ACB name for IMS. The name specified for APPLID= must be the same as the ACBNAME= parameter of the VTAM APPL definition statement. If the ACBNAME= parameter is not specified, the APPLID= name must be the same as the name of the APPL definition statement that is used when defining IMS to VTAM. If the other subsystem is also an IMS, the name specified for APPLID= must be the same as that supplied on the NAME= keyword parameter of that IMS TERMINAL macro statement.

If you choose not to define the APPLID parameter on the COMM macro statement and instead use the job step name of the EXEC statement when initiating the IMS control region, VTAM attempts to match that name with either the ACBNAME= parameter or the name of the VTAM APPL definition statement, as described in the preceding paragraph.

When specifying the receive-any (RECANY) buffer size on the COMM macro, remember that a 28-byte overhead applies to the size of the receive buffers for ISC sessions. Therefore, the RECANY buffer size specified on the NYIMS system definition must be at least 28 bytes larger than the size specified for OUTBUF= on the TERMINAL macro of the SFIMS system definition for NYIMS. When defining SFIMS, the same considerations apply.

Other factors affect the size of the RECANY buffers. Because the specified RECANY buffer size applies to all VTAM devices, the size specified for RECANY might be larger than the size required for ISC due to the needs of other VTAM devices. Also, the FM header size must be added to the maximum data record size for both systems to determine the maximum ISC RECANY size.

The EDTNAME parameter specifies the alias that can be used for ISCEDT in your IMS system. In this system definition, the default name, ISCEDT, is used, making the specification of the EDTNAME= parameter unnecessary.