Memory  cannot  be shared between system images. It is possible to dynamically reallocate  storage resources for z/Architecture LPARs that run operating systems that support dynamic  storage reconfiguration (DSR). This process is supported by z/OS and z/VM. z/VM, in turn,  virtualizes this support to its guests. For more information, see 3.7.5, “LPAR dynamic storage  reconfiguration” on page 106. Operating systems that run as guests of z/VM can use the z/VM capability of implementing  virtual memory to guest virtual machines. The z/VM dedicated real storage can be shared  between guest operating systems. The z14 ZR1 storage allocation and usage possibilities, depending on the image mode, are  listed in Table 3-6. The following modes are provided: In z/Architecture (General, formerly ESA/390 or ESA/390-TPF) mode, storage addressing  is 64-bit, which allows for virtual addresses up to 16 exabytes (16 EB). The 64-bit  architecture theoretically allows a maximum of 16 EB to be used as main storage.  However, the current main storage limit for LPARs is 8 TB for z14 ZR1. The operating  system that runs in z/Architecture mode must support the real storage. Currently, z/OS  supports up to 4 TB$^{7}$ of real storage (z/OS V2R1 and later releases). In CF mode, storage addressing is 64 bit for a CF image that runs at CFCC Level 12 or  later. This configuration allows for an addressing range up to 16 EB. However, the current  z14 ZR1 definition limit for CF LPARs is 1 TB of storage. The following CFCC levels are  supported in a Sysplex with IBM z14 ZR1: Image mode Architecture mode (addressability) Maximum main storage Architecture z14 ZR1 definition z/Architecture  (General) z/Architecture (64-bit) 16 EB 4 TB Coupling facility CFCC (64-bit) 1.5 TB 1 TB Linux only z/Architecture (64-bit) 16 EB 2 TB z/VM z/Architecture (64-bit) 16 EB 2 TB SSC a z/Architecture (64-bit) 16 EB 2 TB Table 3-6 Main storage definition and usage possibilities a. Secure Service Container GLYPH<SM590000> z/Architecture mode GLYPH<SM590000> CF mode – CFCC Level 23, available on z14 (Driver level 36) – CFCC Level 22, available on z14 ZR1 (Driver level 32) – CFCC Level 21, available on z13 and z13s (Driver Level 27) – CFCC Level 20, available for z1 3 servers with Driver Level 22  Restriction: z14 ZR1 does not support direct coupling connectivity to zEC12/zBC12  systems. For more information, see 3.9.1, “Coupling Facility  Control Code” on page 110.  7 1 TB for z/OS V1R13. 104  IBM 14 Model ZR1 Technical Guide