The SYSEVENTs DONTSWAP, OKSWAP, and TRANSWAP control swapping. The choice of mnemonic depends on the period of time for which the address space is to be non-swappable.

For a short period of time (less than one minute), use DONTSWAP to make it non-swappable and OKSWAP to make it swappable.

For an extended period of time (more than one minute), use TRANSWAP to make the address space non-swappable and OKSWAP to make it swappable.

The mnemonics are explained as follows:

DONTSWAP

Notifies SRM that the address space from which this SYSEVENT is issued cannot be swapped out until the system receives a matching OKSWAP for each DONTSWAP issued or until the jobstep ends.

No input parameters are required. One of the following codes will be returned in register 1, byte 3:

Hexadecimal Code	Meaning
00	The request was honored.
04	The request was not honored because it was not for the current address space.
08	The request was not honored because the issuer was not authorized or the outstanding count of DONTSWAP requests had reached its maximum.

OKSWAP

Notifies SRM that the address space from which the SYSEVENT was issued can be considered for swapping.

No input parameters are required. One of the following codes will be returned in register 1, byte 3:

Hexadecimal Code	Meaning
00	The request was honored.
04	The request was not honored because it was not for the current address space.
08	The request was not honored because the issuer was not authorized.

TRANSWAP

Forces a swap out. After the subsequent swap-in, frames are allocated from preferred storage and the address space is non-swappable. TRANSWAP prevents programs from allocating frames in reconfigurable storage. If the program issuing SYSEVENT depends on the transition to complete, you should ensure that register 1 contains the address of an ECB. SYSEVENT will then post this ECB when it swaps out the address space. If no dependency exists, set register 1 to 0 (zero).

One of the following codes will be returned in register 1, byte 3:

Hexadecimal Code	Meaning
00	The request was honored. If an ECB was specified, your program should issue a WAIT macro specifying the same ECB.
04	The transition was previously done or the address space is permanently non-swappable. If an ECB was specified it will not be posted.

If an ECB was specified, the following POST codes may occur in the last three bytes of the ECB:

Hexadecimal Code	Meaning
000000	The transition is complete.
000004	The address space became non-swappable before it could be swapped out.