Format of user data
As part of the general rules for APPC basic conversations, the user data must be in LL-ID-data format (where LL and ID are each two bytes long), and must follow the attach FMH-5 header.
The CICS® DFHCLS4 program requires the user input data stream to fit into the format shown in Figure 1; if it does not, CICS rejects the data. Figure 1. Format of user data.
Note:
- This is an attach FMH-5 header with its data. Data is passed between the PEM client and the CICS PEM server via GDS variables. For information about GDS, see z/OS Communications Server: SNA Programmer's LU 6.2 Guide.
- The GDS record contains GDS data in the format LL-ID-data where:
LL
, which is two bytes long, is the length of the GDS record, including the LL and ID lengths.ID
, which is two bytes long, indicates what the data record represents; for example, X'1221' (sign-on data).
- The GDS data record is itself an LL-ID-data record; in this example, a transaction program
record (or TP record) where:
LL
, which is two bytes long, is the length of the TP record including the LL and ID lengths.ID
which is two bytes long, indicates the function the TP is to perform; for example, X'FF00' (sign-on) or X'FF01' (signon and change password).
- The TP data record is divided up into L-ID-data records (where L and ID are each one byte
long). These are known as subfield (or SF records) where:
L
is the length of the SF record, including theL
andID
lengths.ID
indicates the subfield being passed; for example, X'01' (userid), X'02' (password), and X'06' (new password).
![This figure shows the format of user data for APPC basic conversations.](../graphics/t5jwb0b.gif)