Using the ASCRE macro to create an address space

The ASCRE macro creates an address space. Parameters on the macro allow you to:

Name the address space and specify the first program that is to run in the address space (ASNAME or STPARM parameter).
Specify an address space initialization routine that ASCRE processing calls (INIT parameter).
Provide a routine to control the termination of the address space (TRMEXIT parameter).
- Provide the termination routine with user data (UTOKEN parameter).
Pass a parameter list from the creating program to a program in the new address space (ASPARM or STPARM parameter).
Assign various attribute to the new address space (ATTR parameter).
Set up cross memory linkages between the creating address space and the new address space (AXLIST, TKLIST, and LXLIST parameters).
Provide an address where ASCRE will return output data (ODA parameter).

The required parameters on the ASCRE macro are ASNAME or STPARM, INIT, and ODA. Some comments about these parameters are:

Specify either ASNAME or STPARM.
- ASNAME specifies the address space name, which is also the name of the procedure that identifies the first program to run in the new address space.
- STPARM specifies a parameter string. Although the system does not actually issue a START command, the parameter string consists of START command parameters. This parameter string must begin with the name of the address space.
An operator can use the name of the address space on the DISPLAY A command to display information about the address space. For the syntax of the DISPLAY command, see z/OS MVS System Commands.

Output data from the macro appears at the location specified on the ODA parameter. This data includes two identifiers of the new address space: the ASCB and the STOKEN. The STOKEN is an identifier that is unique within the lifetime of an IPL. The format of the output data area is a 24-byte area that the macro IHAASEO maps as follows:

Offset	Length	Description
X‘00’	8 bytes	The STOKEN of the new address space
X‘08’	4 bytes	The ASCB of the new address space
X‘0C’	4 bytes	Basing for IEZEAECB, the mapping macro for the two ECBs, EAERIMWT and EAEASWT
X‘10’	8 bytes	Reserved

For the format of IHAASEO, see the ASEO data area in See z/OS MVS™ Data Areas in the z/OS® Internet Library: &zosliburl;.

Although INIT is a required parameter, you might not need to write an initialization routine. The address space initialization routine can help you decide whether you need an initialization routine.

Issue the ASCRE macro in a supervisor state program that is executing in primary or AR address space control (ASC) mode. The caller must be in enabled and unlocked TCB mode and must not have an enabled unlocked task (EUT) functional recovery routine (FRR) established. Issue the ASCRE macro only after system initialization is complete.